Database: INSPEC Provider: OCLC Database: INSPEC Ownership: Check the catalogs in your library. Libraries that Own Item: 26 Copyright: Copyright 2002, IEE Accession No: 7135603 INSPEC Abstract No: A2002-03-7630-010 Author(s): Ito, T.; Yokoyama, H.; Sato, T.; Ogata, T. Corp Source: Graduate Sch. of Sci. & Eng., Yamagata Univ., Yonezawa, Japan Title: Influence of the lens effect in a sample with large dielectric constant in a loop-gap resonator on the EPR signal intensity at 700 MHz Source: Applied Magnetic Resonance, vol.21, no.1 p. 97-103 ISSN: 0937-9347 CODEN: APMREI Publication: Austria Language: English Publisher: Springer-Verlag Year: 2001 Copyright No: 0937-9347/01/$1.00+0.20 Treatment: X Experimental Record Type: Journal Paper Abstract: The influence of the lens effect on the electron paramagnetic resonance (EPR) signal intensity was investigated in a loop-gap resonator (LGR) with an inner diameter of 41 mm. The Q-value and EPR signal intensity were measured when the phantoms containing 3-carbamoyl-2,2,5,5-tetramethylpyrrolidin-1-yloxy dissolved in sodium chloride aqueous solutions were put in the LGR. The Q-value and signal intensity reduced with increasing concentrations of sodium chloride in the phantom, indicating that the imaginary part of the dielectric constant is larger in the phantom with the higher concentration of sodium chloride. However, relationships between Q-values of the resonator and EPR signal intensities were not proportional and signal intensities were relatively higher compared with the Q-values. These findings suggest that the signal reduction due to low Q is slightly compensated by the lens effect in the sample with the large real part of the dielectric constant. In the distribution of the signal intensities of a pinpoint sample made of diphenylpicrylhydrazyl in the agar medium containing sodium chloride in the LGR, it was found that the signal intensity decreased according to the distance from the center and the difference in the signal intensity within 10 mm from the center was about 20%, indicating the inhomogeneity of the alternating magnetic field at the center and marginal region in the sample with the large dielectric constant caused by the lens effect (15 Refs.) Descriptor(s): organic compounds; paramagnetic resonance; permittivity; Q-factor Identifier: lens effect; EPR; electron paramagnetic resonance; loop-gap resonator; signal intensity; Q-value; phantoms; 3-carbamoyl-2,2,5,5-tetramethylpyrrolidin-1-yloxy; sodium chloride aqueous solutions; sodium chloride; imaginary part; dielectric constant; diphenylpicrylhydrazyl; agar medium; 700 MHz; 41 mm; NaCl Class Code: A7630 (Electron paramagnetic resonance and relaxation); A7720 (Dielectric permittivity) Chemical Indx: NaCl/bin Cl/bin Na/bin Numerical Ind: frequency 7.0 E+08 Hz; size 4.1 E-02 m -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 442 Copyright: Copyright 2002, IEE Accession No: 7133781 INSPEC Abstract No: A2002-03-0758-004 Author(s): Nesmelov, Yu.E.; Surek, J.T.; Thomas, D.D. Corp Source: Dept. of Biochem., Univ. of Minnesota Med. Sch., Minneapolis, MN, USA Title: Enhanced EPR sensitivity from a ferroelectric cavity insert Source: Journal of Magnetic Resonance, vol.153, no.1 p. 7-14 ISSN: 1090-7807 CODEN: JOMRA4 Publication: USA Language: English Publisher: Academic Press Year: Nov. 2001 Copyright No: 1090-7807/01/$35.00 Treatment: P Practical; X Experimental Record Type: Journal Paper Abstract: We report the development of a simple ferroelectric cavity insert that increases the electron paramagnetic resonance (EPR) sensitivity by an order of magnitude when a sample is placed within it. The insert is a hollow cylinder (length 4.8 mm, outside diameter 1.7 mm, inside diameter 0.6 mm) made from a single crystal of KTaO/sub 3/, which has a dielectric constant of 230 at X-band (9.5 GHz). Its outside dimensions were chosen to produce a resonant frequency in the X-band range, based on electromagnetic field modeling calculations. The insert increases the microwave magnetic field (H/sub 1/) at the center of the insert by a factor of 7.4 when placed in an X-band TM/sub 110/ cavity. This increases the EPR signal for a small (volume 0.13 mu L) unsaturated nitroxide spin label sample by a factor of 64 at constant microwave power, and by a factor of 9.8 at constant H/sub 1/. The insert does not significantly affect the cavity quality factor Q, indicating that this device simply redistributes the microwave fields within the cavity, focusing H/sub 1/ onto the sample inside the insert, thus increasing the filling factor. A similar signal enhancement is obtained in the TM/sub 110/ and TE/sub 102/ cavities, and when the insert is oriented either vertically (parallel to the microwave field) or horizontally (parallel to the DC magnetic field) in the TM/sub 110/ cavity. This order-of-magnitude sensitivity enhancement allows EPR spectroscopy to be performed in conventional high-Q cavities on small EPR samples previously only measurable in loop-gap or dielectric resonators. This is of particular importance for small samples of spin-labeled biomolecules (20 Refs.) Descriptor(s): EPR imaging; EPR spectrometers; ferroelectric devices; muscle; permittivity; spectrometer accessories Identifier: EPR sensitivity; ferroelectric cavity insert; KTaO/sub 3/; dielectric constant; X-band; resonant frequency; electromagnetic field modeling; microwave magnetic field; unsaturated nitroxide spin label; microwave power; microwave fields; filling factor; TM/sub 110/ cavities; TE/sub 102/ cavities; order-of-magnitude sensitivity enhancement; high-Q cavities; loop-gap resonators; dielectric resonators; spin-labeled biomolecules; muscle fiber; electron paramagnetic resonance sensitivity; 4.8 mm; 0.6 mm; 9.5 GHz Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); A8760I (Medical magnetic resonance imaging and spectroscopy); A8780 (Biophysical instrumentation and techniques) Chemical Indx: KTaO3/ss TaO3/ss O3/ss Ta/ss K/ss O/ss Numerical Ind: size 4.8 E-03 m; size 6.0 E-04 m; frequency 9.5 E+09 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 588 Copyright: Copyright 2001, IEE Accession No: 7034148 INSPEC Abstract No: A2001-20-8760I-017 B2001-10-7510N-042 Author(s): Alfonsetti, M.; Del Vecchio, C.; Di Giuseppe, S.; Placidi, G.; Sotgiu, A. Corp Source: Dipt. di Sci. e Tecnologie Biomediche, L'Aquila Univ., Italy Title: A composite resonator for simultaneous NMR and EPR imaging experiments Source: Measurement Science & Technology, vol.12, no.8 p. 1325-9 ISSN: 0957-0233 CODEN: MSTCEP Publication: UK Language: English Publisher: IOP Publishing Year: Aug. 2001 Copyright No: 0957-0233/2001/081325+05$30.00 Treatment: P Practical; X Experimental Record Type: Journal Paper Abstract: Electron paramagnetic resonance imaging (EPRI) and nuclear magnetic resonance imaging (NMRI) are currently used for in vivo spectroscopy and imaging. A multimodal apparatus based on the simultaneous observation of electronic and nuclear signals is very desirable because it combines the ability of NMRI to provide an accurate description of the internal structure of a sample with the ability of EPRI to detect the presence of free radicals and map their distribution. At a given value of the magnetic field B/sub 0/, the electronic and nuclear transitions have very different resonance frequencies. This required the development of a multimodal spectrometer that combined the two spectroscopic modalities. In spite of the complexity of the electronic apparatus involved, the main requirement was for a resonator that allowed the simultaneous irradiation and observation of the signals at the two frequencies with good sensitivity. The EPR section of the composite resonator consists of a one-loop, two-gap resonator tuned to 1 GHz and the NMR section is a solenoid, coaxial to the EPR section, tuned to 1.52 MHz, Both sections have been designed to produce a homogeneous RF field in a cylindrical region of diameter 3 cm and length 4 cm. The RF magnetic fields B/sub 1e/ and B/sub 1n/ are directed along the axis of the magnet, The probe was tested on a phantom comprising two separate regions containing 0.73 g of lithium phthalocyanine powder and 20 ml of an aqueous solution of CuSO/sub 4/, respectively, and both EPR and NMR signals have been collected. Measurements of the sensitivity have also been made (14 Refs.) Descriptor(s): biomedical equipment; biomedical MRI; cavity resonators; EPR imaging; EPR spectrometers; NMR imaging; NMR spectrometers Identifier: EPR imaging; NMR imaging; simultaneous imaging; composite resonator; in vivo spectroscopy; multimodal apparatus; free radicals distribution; multimodal spectrometer; one-loop two-gap resonator; solenoid; homogeneous RF field; cylindrical region; lithium phthalocyanine powder phantom; copper sulphate aqueous solution; Q factor; 1 GHz; 1.52 MHz Class Code: A8760I (Medical magnetic resonance imaging and spectroscopy); A8740 (Biomagnetism); A8770E (Patient diagnostic methods and instrumentation); A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); B7510N; B1320 (Waveguide components) Numerical Ind: frequency 1.0 E+09 Hz; frequency 1.52 E+06 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 442 Copyright: Copyright 2001, IEE Accession No: 7033092 INSPEC Abstract No: A2001-20-0758-003 Author(s): Petryakov, S.; Chzhan, M.; Samouilov, A.; Gunaglong He; Kuppusamy, P.; Zweier, J.L. Corp Source: Dept. of Med., Johns Hopkins Univ. Sch. of Med., Baltimore, MD, USA Title: A bridged loop-gap S-band surface resonator for topical EPR spectroscopy Source: Journal of Magnetic Resonance, vol.151, no.1 p. 124-8 ISSN: 1090-7807 CODEN: JOMRA4 Publication: USA Language: English Publisher: Academic Press Year: July 2001 Copyright No: 1090-7807/2001/$35.00 Treatment: T Theoretical or Mathematical Record Type: Journal Paper Abstract: The design and structure of a bridged loop-gap surface resonator developed for topical EPR spectroscopy and imaging of the distribution and metabolism of spin labels in in vivo skin is reported. The resonator is a one-loop, one-gap bridged structure. A pivoting single loop-coupling coil was used to couple the microwave power to the loop-gap resonant structure. A symmetric coupling circuit was used to achieve better shielding and minimize radiation. The frequency of the resonator can be easily adjusted by trimming the area of the capacitive foil bridge, which overlaps the gap in the cylindrical loop. The working frequency set was 2.2 GHz and the unloaded Q was 720. The B/sub 1/ field of this resonator was measured and spatially mapped by three-dimensional EPR imaging. The resonator is well suited to topical measurements of large biological subjects and is readily applicable for in vivo measurements of free radicals in human skin (12 Refs.) Descriptor(s): biological techniques; EPR imaging; EPR spectroscopy; resonators; skin; spectrometer accessories Identifier: bridged loop-gap S-band surface resonator; topical EPR spectroscopy; spin label distribution; metabolism; in vivo measurement; human skin imaging; one-loop one-gap bridged structure; pivoting single loop-coupling coil; microwave power; loop-gap resonant structure; symmetric coupling circuit; capacitive foil bridge; three-dimensional EPR imaging; biological subjects; free radicals Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); A7630 (Electron paramagnetic resonance and relaxation); A8780 (Biophysical instrumentation and techniques) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: Check the catalogs in your library. Libraries that Own Item: 90 Copyright: Copyright 2001, IEE Accession No: 7025066 INSPEC Abstract No: A2001-19-0758-003 B2001-10-1320-054 Author(s): Lim, Y.C.M.; Mostafavi, R.F.; Mirshekar-Syahkal, D. Corp Source: Dept. of Electron. Syst. Eng., Essex Univ., Colchester, UK Title: Quasi-static numerical analysis of loop-gap resonator Source: AIP Conf. Proc. (USA), AIP Conference Proceedings, no.557A p. 454-9 ISSN: 0094-243X CODEN: APCPCS Publication: USA Language: English Publisher: AIP Conference: Seventh Annual Review of Progress in Quantitative Nondestructive Evaluation Conference Loc: Ames, IA, USA; 16-21 July 2000 Year: 2001 Copyright No: 0094-243X/2001/$18.00 Treatment: T Theoretical or Mathematical Record Type: Conference Paper; Journal Paper Abstract: A new quasi-static technique for the analysis of the loop-gap resonator is presented. For the fundamental mode, the resonator inductance is computed using the finite difference method. The resonator capacitance is obtained from a conformal mapping based expression, modified to account for the ends of the resonator fringing fields. The present technique can generate accurately the magnetic field distribution of the resonator, which is important in some applications. Example results are presented and discussed (6 Refs.) Descriptor(s): boundary-value problems; capacitance; cavity resonators; convergence of numerical methods; EPR spectrometers; field plotting; finite difference methods; inductance; Laplace equations; microwave imaging; NMR spectrometers; nondestructive testing; sample holders Identifier: loop-gap resonator; quasi-static numerical analysis; fundamental mode; resonator inductance; finite difference method; resonator capacitance; conformal mapping based expression; resonator fringing field ends; magnetic field distribution; slotted cylindrical ring resonator; sample holder; NMR; ESR; boundary conditions; Laplace equation; convergence; Q-factor; microwave inspection Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); A0260 (Numerical approximation and analysis); A0750 (Electrical instruments and techniques); A8170L; B1320 (Waveguide components); B5240D (Waveguide and cavity theory); B0290P (Differential equations); B1370; B7310N (Microwave measurement techniques); B0590 (Materials testing) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 442 Copyright: Copyright 2001, IEE Accession No: 6941965 INSPEC Abstract No: A2001-13-0758-001 B2001-07-2130-006 C2001-07-3110G-001 Author(s): Yokoyama, H.; Sato, T.; Ogata, T.; Ohya, H.; Kamada, H. Corp Source: Inst. for Life Support Technol., Yamagata, Japan Title: Automatic coupling control of a loop-gap resonator by a variable capacitor attached coupling coil for EPR measurements at 650 MHz Source: Journal of Magnetic Resonance, vol.149, no.1 p. 29-35 ISSN: 1090-7807 CODEN: JOMRA4 Publication: USA Language: English Publisher: Academic Press Year: March 2001 Copyright No: 1090-7807/2001/$35.00 Treatment: T Theoretical or Mathematical Record Type: Journal Paper Abstract: A coupling coil was fabricated that can electrically change the magnetic coupling with a loop-gap resonator (LGR) for EPR studies at 650 MHz. It is composed of a single-turn coil and a coupling control circuit that includes a varactor diode. The coarse control of the magnetic coupling is made by mechanically changing the distance between the LGR and single-turn coil. The fine control is obtained by changing the capacitance of the varactor diode that is connected in parallel with the single-turn coil. This capacitance is controlled by changing reverse voltage from a variable bias voltage source. Because this can be located far from the resonator, remote control of coupling of the LGR is possible. Automatic coupling control (ACC) was accomplished by negative feedback of the DC component in the radiowaves reflected from the LGR to the coupling control circuit when the LGR was irradiated precisely at its resonant frequency. To accomplish this, automatic frequency control (AFC) is used. In EPR measurements of a phantom that included a physiological saline solution containing a nitroxide radical, it was confirmed that the drifts in the coupling and resonant frequency caused by the perturbation of the resonant nature could be sufficiently compensated by the ACC and AFC systems. In the in vivo EPR studies, it was found that the deviation of coupling at the chest of a mouse is greater than that at the head of a rat, but the ACC system could compensate for the respiratory motions of a living animal (15 Refs.) Descriptor(s): automatic frequency control; capacitors; EPR spectroscopy; feedback; physical instrumentation control; resonators; spectrometer accessories Identifier: automatic coupling control; loop-gap resonator; variable capacitor attached coupling coil; EPR measurements; fabrication; electrical change; magnetic coupling; EPR studies; single-turn coil; coupling control circuit; varactor diode; coarse control; mechanical change; distance; capacitance; reverse voltage; variable bias voltage source; negative feedback; DC component; radiowaves; resonant frequency; automatic frequency control; phantom; physiological saline solution; nitroxide radical; in vivo EPR; mouse chest; rat head; respiratory motions; living animal Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); A0670T (Servo and control devices); B2130 (Capacitors); C3110G (Frequency control); C3380D (Control of physical instruments) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: Check the catalogs in your library. Libraries that Own Item: 110 Copyright: Copyright 2000, IEE Accession No: 6730691 INSPEC Abstract No: A2000-22-0758-001 Author(s): Manoharan, P.T.; Chandramouli, G.V.R. Corp Source: Regional Sophisticated Instrum. Centre, Indian Inst. of Technol., Madras, India Title: Evolution of magnetic resonance spectroscopy Source: PINSA-A (Proceedings of the Indian National Science Academy) Part A (Physical Sciences), vol.65, no.6 p. 613-31 ISSN: 0370-0046 CODEN: PIPSBD Publication: India Language: English Publisher: Indian Natl. Sci. Acad Year: Nov. 1999 Treatment: G General Review Record Type: Journal Paper Abstract: A review of magnetic resonance spectroscopy from its beginning to the current developments is presented. The phenomenological spin-Hamiltonian of nuclear magnetic resonance, the methods and constraints of high resolution NMR, evolution of Fourier transform NMR spectroscopy are presented. A brief introduction to 2D-FT NMR methods like COSY, NOESY and EXSY is given. Magnetic resonance imaging by 2D and 3D-FT NMR spectroscopy is described. EPR spin-Hamiltonian, the advantage of loop-gap resonators over the conventional cavity resonators are presented. The modem trends in EPR spectroscopy, its applications to biological systems, recent developments in EPR spectroscopy with the availability of fast computers and sophisticated EPR components including FT EPR spectroscopy, electron spin echoes, electron spin echo envelop modulation, and 2D-FT EPR spectroscopy are discussed. Electron-Zeeman resolved EPR spectroscopy, EPR imaging technique and in vivo EPR spectroscopy, electron-nuclear double resonance, Mossbauer and nuclear quadrupole resonance spectroscopies also find an expression in this report (58 Refs.) Descriptor(s): biological NMR; biomagnetism; ENDOR; EPR imaging; EPR spectroscopy; Fourier transform spectroscopy; molecular biophysics; Mossbauer spectroscopy; NMR imaging; NMR spectroscopy; nuclear magnetic resonance; nuclear quadrupole resonance; paramagnetic resonance; reviews; spin echo (EPR); two-dimensional spectroscopy Identifier: magnetic resonance spectroscopy; review; phenomenological spin-Hamiltonian; nuclear magnetic resonance; high resolution NMR; Fourier transform NMR; COSY; NOESY; EXSY; magnetic resonance imaging; EPR spin-Hamiltonian; loop-gap resonators; cavity resonators; biological systems; EPR spectroscopy; electron spin echoes; electron spin echo envelop modulation; FT EPR; electron-Zeeman resolved EPR spectroscopy; EPR imaging technique; in vivo EPR; electron-nuclear double resonance; Mossbauer spectroscopy; nuclear quadrupole resonance spectroscopy Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); A8715M (Interactions with radiations at the biomolecular level); A8740 (Biomagnetism) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 1017 Copyright: Copyright 2000, IEE Accession No: 6642888 INSPEC Abstract No: A2000-16-0758-006 Author(s): Willer, M.; Forrer, J.; Keller, J.; Van Doorslaer, S.; Schweiger, A.; Schuhmann, R.; Weiland, T. Corp Source: Lab. fur Phys. Chem., Eidgenossische Tech. Hochschule, Zurich, Switzerland Title: S-band (2-4 GHz) pulse electron paramagnetic resonance spectrometer: Construction, probe head design, and performance Source: Review of Scientific Instruments, vol.71, no.7 p. 2807-17 ISSN: 0034-6748 CODEN: RSINAK Publication: USA Language: English Publisher: AIP Year: July 2000 Copyright No: 0034-6748/2000/71(7)/2807(11)/$17.00 Treatment: P Practical; X Experimental Record Type: Journal Paper Abstract: The design and construction of a combined pulse/continuous wave electron paramagnetic resonance (EPR) spectrometer operating in the 2-4 GHz frequency range (S band) are presented. Details of the microwave bridge are described including a Q-tune arm for adjustments of the microwave coupling during high-power pulse excitation. Factors affecting the microwave resonator construction and the frequency and Q tuning are discussed. The distribution of the electromagnetic field in a bridged loop-gap resonator with a large sample volume for EPR and electron-nuclear double resonance experiments and experiments with B/sub 0/-field steps are determined using numerical calculations. One- and two-dimensional pulse echo experiments are presented and compared with the results obtained with a pulse X-band (8-10 GHz) spectrometer. For weakly coupled nuclei the echo modulation depth increases by about one order of magnitude when lowering the microwave frequency from X band to S band (42 Refs.) Descriptor(s): EPR spectrometers Identifier: S-band pulse electron paramagnetic resonance spectrometer; probe head; microwave bridge; microwave resonator; frequency tuning; Q-factor tuning; electromagnetic field distribution; bridged loop-gap resonator; EPR; ENDOR; one-dimensional pulse echo; two-dimensional pulse echo; ESEEM; 2 to 4 GHz Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques) Numerical Ind: frequency 2.0 E+09 to 4.0 E+09 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: Check the catalogs in your library. Libraries that Own Item: 26 Copyright: Copyright 2000, IEE Accession No: 6458247 INSPEC Abstract No: A2000-03-0758-002 Author(s): Sato, T.; Yokoyama, H.; Ohya, H.; Kamada, H. Corp Source: Yamagata Res. Inst. of Technol., Japan Title: A multilayered element resonator for CW-ESR and longitudinally detected ESR at radio frequency Source: Applied Magnetic Resonance, vol.17, no.1 p. 119-31 ISSN: 0937-9347 CODEN: APMREI Publication: Austria Language: English Publisher: Springer-Verlag Year: 1999 Copyright No: 0937-9347/99/$0.00+0.20 Treatment: A Application; P Practical; X Experimental Record Type: Journal Paper Abstract: The design and evaluation of a multilayered element resonator (MLR), which consists of multiple layers of half-loop conductor plates and insulator sheets, are presented. An MLR and a bridge shielded loop-gap resonator (BLGR), which have similar sizes and resonant frequencies, were fabricated to compare their performances. Using the MLR and the BLGR, the modulation field width and signal intensity of a phantom containing a nitroxide radical were measured by employing a continuous-wave electron spin resonance (CW-ESR) technique at a radio frequency of 300 MHz. Using the same resonators, the longitudinally detected ESR (LODESR) signal intensities of the phantom were also compared. The loaded Q values of the resonators were almost the same. The modulation widths in the MLR were significantly wider than those in the BLGR when the modulation coils were driven at the same voltage. The signal intensities of CW-ESR and LODESR from the phantom in the MLR were significantly greater than those from the BLGR. Since eddy currents disturb the penetration of the modulation field in CW-ESR or detection of changes in magnetization in LODESR observations, these results show that, in the MLR, the eddy currents were suppressed to a greater degree than in the BLGR (21 Refs.) Descriptor(s): eddy currents; EPR spectrometers; resonators Identifier: CW-ESR; longitudinally detected ESR; multilayered element resonator; radio frequency; half-loop conductor plates; insulator sheets; multiple layers; bridge shielded loop-gap resonator; modulation field width; signal intensity; nitroxide radical; eddy currents; 300 MHz Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); A7630 (Electron paramagnetic resonance and relaxation) Numerical Ind: frequency 3.0 E+08 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 429 Copyright: Copyright 1999, IEE Accession No: 6264319 INSPEC Abstract No: A1999-13-8760I-014 B1999-07-7510N-012 Author(s): Diodato, R.; Alecci, M.; Brivati, J.A.; Varoli, V.; Sotgiu, A. Corp Source: INFM, Univ. dell'Aquila, Italy Title: Optimization of axial RF field distribution in low-frequency EPR loop-gap resonators Source: Physics in Medicine and Biology, vol.44, no.5 p. N69-75 ISSN: 0031-9155 CODEN: PHMBA7 Publication: UK Language: English Publisher: IOP Publishing Year: May 1999 Copyright No: 0031-9155/99/050069+07$19.50 Treatment: X Experimental Record Type: Journal Paper Abstract: A novel coupling method that optimizes the axial RF distribution of low-frequency EPR loop-gap resonators is presented. It consists of a resonant coupling loop positioned at the centre of a two-section loop-gap resonator. This arrangement ensures a symmetrical distribution of the radio frequency field along the axis of the resonator. The design of a central coupling system suitable for EPR resonators operating at about 220 MHz is described. Experimental results show that with the central coupling system the RF field is symmetrical and has a very good axial homogeneity (100% of the resonator length) (16 Refs.) Descriptor(s): biomedical imaging; cavity resonators; EPR imaging; EPR spectrometers Identifier: coupling method; low-frequency EPR loop-gap resonators; resonant coupling loop; centre; two-section loop-gap resonator; symmetrical distribution; central coupling system; axial homogeneity; resonator length; optimization; EPR imaging; axial RF field distribution; 220 MHz Class Code: A8760I (Medical magnetic resonance imaging and spectroscopy); A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); A8780 (Biophysical instrumentation and techniques); A8770E (Patient diagnostic methods and instrumentation); B7510N; B5240D (Waveguide and cavity theory) Numerical Ind: frequency 2.2 E+08 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: Check the catalogs in your library. Libraries that Own Item: 1 Copyright: Copyright 1999, IEE Accession No: 6241945 INSPEC Abstract No: A1999-12-8780-003 Author(s): Ogata, T.; Ohya-Nishiguchi, H. Corp Source: Graduate Sch. of Eng., Yamagata Univ., Japan Title: In vivo ESR spatiotemporal measurements to analyze the dynamics of free radicals in living systems Source: Medical Imaging Technology, vol.17, no.1 p. 35-42 ISSN: 0288-450X CODEN: MITEET Publication: Japan Language: Japanese Publisher: Japanese Soc. Med. Imaging Technol Year: Jan. 1999 Treatment: P Practical Record Type: Journal Paper Abstract: Electron spin resonance (ESR) spatiotemporal measurements are reviewed in this paper. ESR spatiotemporal analysis has been developed to investigate the dynamics of free radicals in vivo. The core techniques of the analysis are the developments of a rapid field-scan in vivo ESR spectrometer and an imaging system which have been constructed by introducing a microwave frequency lower than 1 GHz, and new resonators such as loop-gap type and surface-coil type. Two methods have been applied for rats or mice receiving the administration of free radical probes: One is a method that the kinetic constant of the probe at a target position is determined from the time course of the gray scale value in a series of ESR images. Second is that the ESR signal of the probe is directly observed by placing a small sensor at a target position. For typical example, the rate constants of first-order kinetics in rat's brain were determined for the probe which could enter the brain through the blood-brain barrier (45 Refs.) Descriptor(s): biochemistry; biological techniques; blood; brain; EPR spectroscopy; free radicals Identifier: in vivo ESR spatiotemporal measurements; free radicals dynamics; living systems; loop-gap resonator; surface-coil resonator; mice; rats; gray scale value; rate constants; blood-brain barrier; imaging system; biological research technique; 1 GHz Class Code: A8780 (Biophysical instrumentation and techniques); A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); A3330 (Electron paramagnetic resonance and relaxation of molecules); A8715M (Interactions with radiations at the biomolecular level) Numerical Ind: frequency 1.0 E+09 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: Check the catalogs in your library. Libraries that Own Item: 52 Copyright: Copyright 1999, IEE Accession No: 6191945 INSPEC Abstract No: A1999-08-8760I-021 B1999-04-7510N-061 C1999-04-7330-255 Author(s): Yokoyama, H.; Sato, T.; Ohya-Nishiguchi, H.; Kamada, H. Corp Source: Inst. of Life Support Technol., Yamagata Univ., Yonezawa, Japan Title: In vivo 300 MHz longitudinally detected ESR-CT imaging in the head of a rat treated with a nitroxide radical Source: Magnetic Resonance Materials in Physics, Biology and Medicine, vol.7, no.2 p. 63-8 ISSN: 1352-8661 CODEN: MAGMEY Publication: Netherlands Language: English Publisher: Elsevier Year: Dec. 1998 Copyright No: 1352-8661/98/$19.00 Treatment: X Experimental Record Type: Journal Paper Abstract: In vivo longitudinally detected ESR (LODESR)-CT system operating at 300 MHz was developed, based on the combination of a bridged loop-gap resonator and a pair of saddle-type pickup coils (STPCs). The sensitivity distribution of the STPCs was simulated on the basis of a magnetic dipole model. A LODESR-CT image of a phantom (a physiological saline solution of a nitroxide radical) was satisfactorily corrected by using the simulation result. LODESR-CT images of the head of a rats, in which nitroxide radical was injected intraperitonally, were also obtained through the correction in the same manner. This is the first in vivo CT (i.e, three-dimensional imaging) study with a 300 MHz ESR (15 Refs.) Descriptor(s): biomedical MRI; computerised tomography; EPR imaging; image reconstruction Identifier: rat head; nitroxide radical treated; in vivo longitudinally detected ESR-CT imaging; LODESR-CT system; bridged loop-gap resonator; saddle-type pickup coils; sensitivity distribution; magnetic dipole model; physiological saline solution phantom; three-dimensional imaging; 300 MHz Class Code: A8760I (Medical magnetic resonance imaging and spectroscopy); A8740 (Biomagnetism); A8770E (Patient diagnostic methods and instrumentation); A8780 (Biophysical instrumentation and techniques); B7510N; B6135; C7330 (Biology and medical computing); C5260B (Computer vision and image processing techniques) Numerical Ind: frequency 3.0 E+08 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 215 Copyright: Copyright 1999, IEE Accession No: 6165482 INSPEC Abstract No: A1999-06-8760I-037 B1999-03-7510N-102 C1999-03-7330-417 Author(s): Joensuu, R.P.; Sepponen, R.E.; Lamminen, A.E.; Savolainen, S.E.; Standertskjold-Nordenstam, C.-G.M. Corp Source: Dept. of Radiol., Helsinki Univ., Finland Title: High-accuracy MR tracking of interventional devices: the Overhauser marker enhancement (OMEN) technique Source: Magnetic Resonance in Medicine, vol.40, no.6 p. 914-21 ISSN: 0740-3194 CODEN: MRMEEN Publication: USA Language: English Publisher: Williams & Wilkins Year: Dec. 1998 Copyright No: 0740-3194/98/$3.00 Treatment: P Practical; X Experimental Record Type: Journal Paper Abstract: A new technique for visualization of interventional devices in magnetic resonance imaging is presented. Determination of the position of an invasive device is made possible by incorporating into the device a small marker that emits the NMR signal. This signal is enhanced by the use of the Overhauser phenomenon. This technique differs from the earlier reported techniques for marking interventional instruments in the sense that the contrast between the marker and tissue is not based on different relaxation rates, but on NMR signal enhancement. A prototype marker was constructed and inserted into an inductively fed loop-gap resonator that couples saturation energy with the marker. Circuit analogies are presented that model the Overhauser phenomenon and the coupling circuit. In vitro experiments demonstrated that the marker is visible in MR images up to a slice thickness of 50 mm when inserted in excised animal liver and fat tissues (30 Refs.) Descriptor(s): biomedical equipment; biomedical MRI; image enhancement; medical image processing; nuclear Overhauser effect; position measurement; tracking Identifier: high-accuracy MR tracking; interventional devices; Overhauser marker enhancement technique; invasive device position determination; tissue/marker contrast; coupling circuit; in vitro experiments; slice thickness; magnetic resonance imaging; excised animal liver; fat tissues; medical diagnostic imaging; inductively fed loop-gap resonator; saturation energy; device visualization; circuit analogies; 50 mm Class Code: A8760I (Medical magnetic resonance imaging and spectroscopy); A8770E (Patient diagnostic methods and instrumentation); A8740 (Biomagnetism); B7510N; B6135; B7320C (Spatial variables measurement); C7330 (Biology and medical computing); C5260B (Computer vision and image processing techniques) Numerical Ind: size 5.0 E-02 m -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 442 Copyright: Copyright 1998, IEE Accession No: 6093983 INSPEC Abstract No: A9901-0758-005 Author(s): Piasecki, W.; Froncisz, W.; Hubbell, W.L. Corp Source: Dept. of Biophys., Jagiellonian Univ., Krakow, Poland Title: A rectangular loop-gap resonator for EPR studies of aqueous samples Source: Journal of Magnetic Resonance, vol.134, no.1 p. 36-43 ISSN: 1090-7807 CODEN: JOMRA4 Publication: USA Language: English Publisher: Academic Press Year: Sept. 1998 Copyright No: 1090-7807/98/$25.00 Treatment: T Theoretical or Mathematical Record Type: Journal Paper Abstract: A new rectangular geometry of the loop-gap resonator for the use with a flat cell has been developed. Maxwell's equations for the resonators with two, four, six, and eight gaps have been solved assuming the existence of only the magnetic z-component. The formulas obtained were numerically solved for the electric and magnetic field distributions over the cross-sections of the resonators. The presence of a nodal plane for the electric field in the center of the resonator allows the use of a hat cell instead of a capillary for EPR measurements. Using the field distributions obtained, the quality factor and EPR signal amplitude for various shapes and gap numbers for the resonators containing a flat cell filled with water were examined numerically. This allowed finding the geometry that yields the maximum EPR signal intensity. Several X-band resonators were built in order to verify the results obtained theoretically. The experiments confirmed the ability of a novel resonant structure to accommodate a flat cell filled with an aqueous sample. It has been found that the optimum aqueous sample volume for the X-band rectangular loop-gap resonator equals 16 mm/sup 3/. For a saturable aqueous sample this gives a fourfold improvement in the S/N ratio over the circular 1 mm i.d. loop-gap resonator equipped with 0.6 mm i.d. capillary (12 Refs.) Descriptor(s): cavity resonators; electric fields; EPR spectrometers; EPR spectroscopy; magnetic fields; Maxwell equations; paramagnetic resonance; Q-factor; spectral line intensity; spectrometer accessories Identifier: rectangular loop-gap resonator; EPR studies; aqueous samples; rectangular geometry; loop-gap resonator; Maxwell's equations; magnetic z-component; magnetic field distribution; electric field distributions; resonators; nodal plane; electric field; hat cell; EPR measurements; field distributions; quality factor; EPR signal amplitude; gap numbers; flat cell; EPR signal intensity; X-band resonators; resonant structure; aqueous sample; optimum aqueous sample volume; X-band rectangular loop-gap resonator; saturable aqueous sample; fourfold improvement; sinal-to-noise ratio; 1 mm; 0.6 mm Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); A3330 (Electron paramagnetic resonance and relaxation of molecules); A3370F (Molecular lifetimes, absolute and relative line and band intensities) Numerical Ind: size 1.0 E-03 m; size 6.0 E-04 m -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 1017 Copyright: Copyright 1998, IEE Accession No: 6060635 INSPEC Abstract No: A9823-0758-007 Author(s): Elger, G.; Torring, J.T.; Mobius, K. Corp Source: Inst. fur Experimentalphys., Freie Univ. Berlin, Germany Title: Novel loop-gap probe head for time-resolved electron paramagnetic resonance at 9.5 GHz Source: Review of Scientific Instruments, vol.69, no.10 p. 3637-41 ISSN: 0034-6748 CODEN: RSINAK Publication: USA Language: English Publisher: AIP Year: Oct. 1998 Copyright No: 0034-6748/98/69(10)/3637(5)/$15.00 Treatment: N New Development; X Experimental Record Type: Journal Paper Abstract: A novel probe head with a two-loop-one-gap resonator for X-band (9.5 GHz) time-resolved transient electron paramagnetic resonance measurements with direct detection is described. The low quality factor Q of the resonator allows time resolution in the order of 10 ns while the high filling factor guarantees a sensitivity which is at least comparable to that of conventional cavity resonators. A novel feature of the resonator is the coupling mechanism which exploits the field distribution in the microwave shield. The type of the resonator and the microwave coupling scheme chosen provide high mechanical stability of the setup. This is particularly important for pulsed laser excitation and gas stream cooling of the sample. The advantages of the probe head are demonstrated by relaxation measurements on the photoexcited triplet state of zinc-tetratolylporphyrin, for which the high time resolution allows the determination of fast anisotropic relaxation. This relaxation behavior can be attributed to the dynamic Jahn-Teller effect (22 Refs.) Descriptor(s): cavity resonators; EPR spectrometers; Q-factor; time resolved spectroscopy Identifier: loop-gap probe head; X-band; time-resolved transient electron paramagnetic resonance; direct detection; quality factor; filling factor; cavity resonator; microwave shield; microwave coupling; mechanical stability; gas stream cooling; pulsed laser excitation; photoexcited triplet state; zinc tetratolylporphyrin; anisotropic relaxation measurement; dynamic Jahn-Teller effect; 9.5 GHz Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques) Numerical Ind: frequency 9.5 E+09 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 1017 Copyright: Copyright 1998, IEE Accession No: 6038699 INSPEC Abstract No: A9821-0758-002 Author(s): Shane, J.J.; Gromov, I.; Vega, S.; Goldfarb, D. Corp Source: Dept. of Chem. Phys., Weizmann Inst. of Sci., Rehovot, Israel Title: A versatile pulsed X-band ENDOR spectrometer Source: Review of Scientific Instruments, vol.69, no.9 p. 3357-64 ISSN: 0034-6748 CODEN: RSINAK Publication: USA Language: English Publisher: AIP Year: Sept. 1998 Copyright No: 0034-6748/98/69(9)/3357(8)/$15.00 Treatment: P Practical; X Experimental Record Type: Journal Paper Abstract: A versatile high power X-band (8.5-9.5 GHz) pulsed EPR/ENDOR (electron-nuclear double resonance) spectrometer which can generate hundreds of microwave (MW) and rf pulses is described. The pulse programmer is constructed from a word generator with 32 channels and 4 ns resolution, coupled to five digital delay generators which can produce a total of ten pulses with a resolution better than 1 ns. The spectrometer contains two MW and two rf channels that allow independent variation of the frequency, amplitude, and phase of the MW and rf pulses. The ENDOR probe head is based on a bridged loop gap (BLG) resonator, coupling is achieved via a coupling loop connected to a waveguide, and the rf coil serves as a MW shield as well. The adjustment of the coupling is done by an up/down motion of the of the resonator assembly with respect to the fixed coupling loop. A flexible and user friendly data acquisition program written in C++ (Borland version 4.5), which uses the Windows-95 Multiple Document Interface (MDI) programming model, was developed to run the spectrometer. This program allows easy programming of any pulse sequence with sophisticated phase cycling. The performance of the spectrometer is demonstrated by two experiments. The first is the triple resonance hyperfine-selective (HS) ENDOR experiment carried out on a frozen solution of the copper protein laccase. The second is the two-dimensional hyperfine-ENDOR (HYEND) correlation experiment performed on a single crystal of gamma -irradiated malonic acid (24 Refs.) Descriptor(s): data acquisition; ENDOR; magnetic resonance spectrometers; spectroscopy computing Identifier: probe head; high power X-band ENDOR spectrometer; microwave pulse generation; RF pulse generation; pulse programmer; word generator; bridged loop gap resonator; data acquisition; C/sup ++/ program; Windows-95 Multiple Document Interface; triple resonance hyperfine-selective experiment; copper protein laccase frozen solution; two-dimensional hyperfine-ENDOR correlation; gamma -irradiated malonic acid single crystal; phase cycling; 8.5 to 9.5 GHz Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); A7670D (Electron-nuclear double resonance (ENDOR) (condensed matter)); A0650D (Data gathering, processing, and recording, data displays including digital techniques) Numerical Ind: frequency 8.5 E+09 to 9.5 E+09 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 588 Copyright: Copyright 1998, IEE Accession No: 5950914 INSPEC Abstract No: A9815-0758-005 Author(s): Diodato, R.; Alecci, M.; Brivati, J.A.; Sotgiu, A. Corp Source: Dipt. di Sci. e Tecnologie Biomed., L'Aquila Univ., Italy Title: Resonant inductive coupling of RF EPR resonators in the presence of electrically conducting samples Source: Measurement Science & Technology, vol.9, no.5 p. 832-7 ISSN: 0957-0233 CODEN: MSTCEP Publication: UK Language: English Publisher: IOP Publishing Year: May 1998 Copyright No: 0957-0233/98/050832+06$19.50 Treatment: P Practical; X Experimental Record Type: Journal Paper Abstract: A new method of matching for radio frequency EPR resonators is proposed. It uses resonant inductive coupling and is particularly suitable for studies with lossy conducting samples. The equivalent circuit of the resonant inductive coupling method is presented and a theoretical analysis of the equations that produce the critical coupling coefficient is discussed. A prototype resonant inductive coupling suitable for loop gap resonators operating at about 200 MHz has been developed and tested. Experimental results obtained with saline solutions show the advantages of resonant inductive coupling in terms of the coupling coefficient, RF magnetic field amplitude and field homogeneity. This matching method has been especially designed for CW EPR applications, in which the adoption of critical coupling is important for optimization of sensitivity. Moreover, resonant inductive coupling should also produce benefits for pulsed EPR studies (24 Refs.) Descriptor(s): cavity resonators; EPR spectrometers; equivalent circuits; impedance matching Identifier: RF EPR resonators; resonant inductive coupling; electrically conducting samples; matching method; lossy conducting samples; equivalent circuit; critical coupling coefficient; prototype coupling; loop gap resonators; saline solutions; RF magnetic field amplitude; field homogeneity; CW EPR applications; optimization of sensitivity; pulsed EPR studies; impedance matching; 200 MHz Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques) Numerical Ind: frequency 2.0 E+08 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: Check the catalogs in your library. Libraries that Own Item: 26 Copyright: Copyright 1998, IEE Accession No: 5814040 INSPEC Abstract No: A9805-0758-004 Author(s): Grishin, Yu.; Kay, C.W.M.; Doubinskii, A.A.; Mobius, K. Corp Source: Inst. of Chem. Kinetics & Combustion, Novosibirsk, Russia Title: A novel loop-gap resonator probehead for EPR and ENDOR at X-band Source: Applied Magnetic Resonance, vol.13, no.3-4 p. 387-92 ISSN: 0937-9347 CODEN: APMREI Publication: Austria Language: English Publisher: Springer-Verlag Year: 1997 Copyright No: 0937-9347/97/$0.00+0.20 Treatment: P Practical Record Type: Journal Paper Abstract: An EPR and ENDOR probehead with a loop-gap resonator for X-band is described. The novel feature of the construction is that an iris-type coupling of the resonator is used instead of the conventional antenna coupling. The ENDOR coil combines the role of creating the radiofrequency field and that of a shield for the microwave loop-gap structure. Hence, in order to accommodate the iris and waveguide, a pair of RF coils is used in conjunction with a reduced waveguide with dielectric filling. This arrangement simplifies matching the resonator to the microwave bridge, and standard EPR cryostats can be used making sample manipulation more convenient (22 Refs.) Descriptor(s): cavity resonators; coils; dielectric-loaded waveguides; ENDOR; EPR spectrometers; loop antennas; waveguide antennas Identifier: loop-gap resonator probehead; EPR; ENDOR; X-band; iris-type coupling; microwave loop-gap structure shield; radiofrequency field creation; ENDOR coil; RF coils; reduced waveguide; dielectric filling; microwave bridge Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 948 Copyright: Copyright 1997, IEE Accession No: 5777395 INSPEC Abstract No: A9802-3330-001 Author(s): Delfs, C.D.; Bramley, R. Corp Source: Res. Sch. of Chem., Australian Nat. Univ., Canberra, ACT, Australia Title: Zero-field electron magnetic resonance spectra of copper carboxylates Source: Journal of Chemical Physics, vol.107, no.21 p. 8840-7 ISSN: 0021-9606 CODEN: JCPSA6 Publication: USA Language: English Publisher: AIP Year: 1 Dec. 1997 Copyright No: 0021-9606/97/107(21)/8840/8/$10.00 Treatment: X Experimental Record Type: Journal Paper Abstract: The design of a new zero-field electron magnetic resonance spectrometer including cryogenic capabilities and a new tuning mechanism for sweeping over approximately two octaves is described. The tuning mechanism is based on a one-loop, two-gap resonator mounted on quartz rods in such a manner that rotating the rods changes the width of the gap and the resonant frequency of the resonator. The spectrometer was used to measure the zero-field emr spectra of several copper carboxylate dimers at 90 K and 70 K. The parallel hyperfine structure was well resolved in all of the spectra and this allowed accurate determination of D, E, and A. Al was found to be poorly defined in general and least square refinements attached large errors to this term in the spin Hamiltonian. The zero-field terms in the spin Hamiltonian at 90 K were determined to be D=9.828 GHz, E=83 MHz, A/sub ££/=217 MHz for [Cu(CH/sub 3/CO/sub 2/)/sub 2/(CO(NH/sub 2/)/sub 2/)]/sub 2/.2H/sub 2/O; D=9.985 GHz, E=43 MHz, A/sub ££/=221 MHz for [Cu(C/sub 2/H/sub 5/CO/sub 2/)/sub 2/(H/sub 2/O)]/sub 2/; D=10.107 GHz, E=49 MHz, A/sub ££/=218 MHz for [Cu(C/sub 2/H/sub 5/CO/sub 2/)/sub 2/(CO(NH/sub 2/)/sub 2/)]/sub 2/; D=9.979 GHz, E=192 MHz, A/sub ££/=223 MHz for [Cu(C/sub 6/H/sub 5/CO/sub 2/)/sub 2/(C/sub 6/H/sub 5/CO/sub 2/H)]/sub 2/. A model which assumes A/sub perpendicular to /=0 is discussed in detail as it was found that all of the features observed in the spectra could be interpreted using simple explicit expressions derived from the model (31 Refs.) Descriptor(s): copper compounds; hyperfine structure; least squares approximations; magnetic resonance; paramagnetic resonance; spin Hamiltonians Identifier: zero-field electron magnetic resonance spectra; copper carboxylates; cryogenic capabilities; tuning mechanism; one-loop two-gap resonator; quartz rods; hyperfine structure; least square refinements; spin Hamiltonian; [Cu(CH/sub 3/CO/sub 2/)/sub 2/(CO(NH/sub 2/)/sub 2/)]/sub 2/.2H/sub 2/O; [Cu(C/sub 2/H/sub 5/CO/sub 2/)/sub 2/(H/sub 2/O)]/sub 2/; [Cu(C/sub 2/H/sub 5/CO/sub 2/)/sub 2/(CO(NH/sub 2/)/sub 2/)]/sub 2/; [Cu(C/sub 6/H/sub 5/CO/sub 2/)/sub 2/(C/sub 6/H/sub 5/CO/sub 2/H)]/sub 2/; 90 to 70 K Class Code: A3330 (Electron paramagnetic resonance and relaxation of molecules); A7630 (Electron paramagnetic resonance and relaxation); A3520S (Molecular hyperfine and fine-structure constants); A7510D (Crystal-field theory and spin Hamiltonians (magnetism)) Numerical Ind: temperature 7.0 E+01 to 9.0 E+01 K -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 442 Copyright: Copyright 1997, IEE Accession No: 5734930 INSPEC Abstract No: A9723-0765-015 Author(s): Borbat, P.P.; Crepeau, R.H.; Freed, J.H. Corp Source: Baker Lab. of Chem., Cornell Univ., Ithaca, NY, USA Title: Multifrequency two-dimensional Fourier transform ESR: an X/Ku-Band spectrometer Source: Journal of Magnetic Resonance, vol.127, no.2 p. 155-67 ISSN: 1090-7807 CODEN: JOMRA4 Publication: USA Language: English Publisher: Academic Press Year: Aug. 1997 Copyright No: 1090-7807/97/$25.00 Treatment: P Practical; X Experimental Record Type: Journal Paper Abstract: A two-dimensional Fourier Transform ESR (2D FT ESR) spectrometer operating at 9.25 and 17.35 GHz is described. The Ku-band bridge uses an efficient heterodyne technique wherein 9.25 GHz is the intermediate frequency. At Ku-band the sensitivity is increased by almost an order of magnitude. One may routinely collect a full 2D ELDOR spectrum in less than 20 min for a sample containing 0.5-5 nmol of nitroxide spin-probe in the slow-motional regime. Broad spectral coverage at Ku-band is obtained by use of a bridged loop-gap resonator (BLGR) and of a dielectric ring resonator (DR). It is shown that an even more uniform spectral excitation is obtained by using shorter microwave pulses of about 3 ns duration. The dead-time at Ku-band is just 30-40 ns, yielding an improved SNR in 2D ELDOR spectra of nitroxide spin-probes with T/sub 2/ as short as 20-30 ns. A comparison of 2D ELDOR spectra obtained at 9.25 and 17.35 GHz for spin-labeled phospholipid probes (16PC) in 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG) membrane vesicles showed that both spectra could be satisfactorily simulated using the same set of model parameters even though they are markedly different in appearance. The improved sensitivity and shorter dead-time at Ku-band made it possible to obtain orientation-dependent 2D ELDOR spectra of the Cholestane (CSL) spin-probe in macroscopically aligned lipid bilayers of egg yolk PC using samples containing only 1 mg of lipid and just 5 nmol of spin probe (38 Refs.) Descriptor(s): biomembranes; EPR spectrometers; Fourier transform spectrometers; lipid bilayers; two-dimensional spectroscopy Identifier: multifrequency two-dimensional Fourier transform ESR; X-Band spectrometer; Ku-Band spectrometer; Ku-band bridge; heterodyne technique; intermediate frequency; full 2D ELDOR spectrum; slow-motional regime; bridged loop-gap resonator; broad spectral coverage; sensitivity; dielectric ring resonator; microwave pulses; dead-time; 2D ELDOR spectra; spin-labeled phospholipid probe; 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol membrane vesicles; orientation-dependent 2D ELDOR spectra; cholestane spin-probe; macroscopically aligned lipid bilayers; egg yolk; 9.25 GHz; 17.35 GHz Class Code: A0765 (Optical spectroscopy and spectrometers); A8720 (Membrane biophysics) Numerical Ind: frequency 9.25 E+09 Hz; frequency 1.735 E+10 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 442 Copyright: Copyright 1997, IEE Accession No: 5720340 INSPEC Abstract No: A9722-7630-002 Author(s): Sturm, G.; Lotz, A.; Voitlander, J. Corp Source: Inst. fur Phys. Chem., Munchen Univ., Germany Title: Pulsed EPR with field cycling and a bridged loop-gap resonator made by chemical deposition of silver Source: Journal of Magnetic Resonance, vol.127, no.1 p. 105-8 ISSN: 1090-7807 CODEN: JOMRA4 Publication: USA Language: English Publisher: Academic Press Year: July 1997 Copyright No: 1090-7807/97/$25.00 Treatment: X Experimental Record Type: Journal Paper Abstract: This paper describes the measurement of the zero-field electron spin-lattice relaxation time of a coal sample by pulsed EPR under field-cycling conditions. The detection system uses an inexpensive homebuilt bridged loop-gap resonator made by chemical deposition of silver (11 Refs.) Descriptor(s): coal; electron spin-lattice relaxation; paramagnetic resonance Identifier: pulsed EPR; field cycling; bridged loop-gap resonator; Ag chemical deposition; zero-field electron spin-lattice relaxation time; coal sample; homebuilt bridged loop-gap resonator Class Code: A7630 (Electron paramagnetic resonance and relaxation) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 234 Copyright: Copyright 1997, IEE Accession No: 5711895 INSPEC Abstract No: A9722-8780-004 Author(s): Yokoyama, H.; Sato, T.; Tsuchihashi, N.; Ogata, T.; Ohya-Nishiguchi, H.; Kamada, H. Corp Source: Inst. for Life Support Technol., Yamagata Technopolis Found., Japan Title: A CT using longitudinally detected ESR (LODESR-CT) of intraperitoneally injected nitroxide radical in a rat's head Source: Magnetic Resonance Imaging, vol.15, no.6 p. 701-8 ISSN: 0730-725X CODEN: MRIMDQ Publication: USA Language: English Publisher: Elsevier Year: 1997 Copyright No: 0730-725X/97/$17.00+.00 Treatment: P Practical Record Type: Journal Paper Abstract: The authors have developed an in vivo longitudinally detected ESR (LODESR) imaging system operating at 700 MHz based on a loop-gap resonator and a pair of saddle-type pickup coils. A good linear relationship between the LODESR signal intensity and the applied power in a range up to 15.8 W was obtained. The detection of LODESR signals was barely affected by variations in the resonant properties. The characteristic of LODESR is suitable for in vivo examination. Using this system, the authors succeeded in obtaining LODESR-CT images of the head region of a rat after the intraperitoneal injection of a nitroxide radical (17 Refs.) Descriptor(s): biological techniques; computerised tomography; EPR spectroscopy Identifier: CT; longitudinally detected ESR; intraperitoneally injected nitroxide radical; rat head region; resonant properties variation; saddle-type pickup coils; loop-gap resonator; intraperitoneal injection; 700 MHz; 15.8 W Class Code: A8780 (Biophysical instrumentation and techniques) Numerical Ind: frequency 7.0 E+08 Hz; power 1.58 E+01 W -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: Check the catalogs in your library. Libraries that Own Item: 52 Copyright: Copyright 1997, IEE Accession No: 5638620 INSPEC Abstract No: A9717-8760I-005 B9709-7510B-011 Author(s): Alecci, M.; Lurie, D.J.; Nicholson, I.; Placidi, G.; Sotgiu, A. Corp Source: Dept. of Biomed. Phys. & Bioeng., Aberdeen Univ., UK Title: Young investigator award presentation at the 13th annual meeting of the ESMRMB, September 1996, Prague. A proton-electron double-resonance imaging apparatus with simultaneous multiple electron paramagnetic resonance irradiation at 10 mT Source: Magnetic Resonance Materials in Physics, Biology, and Medicine, vol.4, no.3-4 p. 187-93 ISSN: 1352-8661 CODEN: MRBMEQ Publication: UK Language: English Publisher: Chapman & Hall Year: Sept.-Dec. 1996 Treatment: P Practical Record Type: Journal Paper Abstract: The detection of free radicals in vivo is very important for the study of many physiologic and pathologic conditions. Free radicals have been implicated in a number of diseases such as ischemia, inflammation, kidney damage, and cancer. Proton-electron double-resonance imaging (PEDRI) allows the indirect detection of free radicals via the Overhauser effect. Nitroxide free radicals used for in vivo PEDRI studies present spectra with two or three lines, but most PEDRI experiments performed to date have used only single-line electron paramagnetic resonance (EPR) irradiation. There is theoretical evidence that simultaneous irradiation of multiple EPR transitions could increase the maximum achievable PEDRI enhancement. From the experimental point of view, this requires the combined use of a suitable multiple-frequency EPR source and a multiple-tuned EPR resonator. A novel radiofrequency (RF) triple-tuned loop-gap resonator for use in PEDRI has recently been developed, and dynamic nuclear polarization (DNP) data were reported. Here, the authors describe a new PEDRI apparatus, equipped with a triple-tuned resonator, that is suitable for simultaneous double- or triple-EPR irradiation of nitroxide free radicals. In particular, the details of the EPR hardware used to generate the two or three EPR frequencies are given, and PEDRI images obtained with simultaneous multiple EPR irradiation are shown. Moreover, DNP experimental results showing the increase of the enhancement as a function of the EPR power for single and simultaneous double EPR irradiation are presented. The main goal of this apparatus is to improve the sensitivity and/or to reduce EPR irradiation power in a PEDRI experiment. This is likely to be particularly important in future biologic applications of PEDRI where the applied power must be optimized to reduce sample heating (21 Refs.) Descriptor(s): biomedical equipment; biomedical imaging; paramagnetic resonance Identifier: proton-electron double-resonance imaging apparatus; multiple electron paramagnetic resonance irradiation; ischemia; inflammation; kidney damage; cancer; nitroxide free radicals; Overhauser effect; multiple-tuned EPR resonator; radiofrequency triple-tuned loop-gap resonator; medical diagnostic imaging; medical instrumentation; 10 mT Class Code: A8760I (Medical magnetic resonance imaging and spectroscopy); A0110C (Announcements, news, and awards); A8770E (Patient diagnostic methods and instrumentation); B7510B (Radiation and radioactivity applications in biomedicine) Numerical Ind: magnetic flux density 1.0 E-02 T -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 1017 Copyright: Copyright 1997, IEE Accession No: 5590380 INSPEC Abstract No: A9713-0758-002 B9707-1320-012 Author(s): Weis, V.; Mittelbach, W.; Claus, J.; Mobius, K.; Prisner, T. Corp Source: Inst. fur Experimentalphys., Berlin, Germany Title: Probehead with interchangeable tunable bridged loop-gap resonator for pulsed zero-field optically detected magnetic resonance experiments on photoexcited triplet states Source: Review of Scientific Instruments, vol.68, no.5 p. 1980-5 ISSN: 0034-6748 CODEN: RSINAK Publication: USA Language: English Publisher: AIP Year: May 1997 Copyright No: 0034-6748/97/68(5)/1980/6/$10.00 Treatment: X Experimental Record Type: Journal Paper Abstract: Conventional zero-field optically detected magnetic resonance (ODMR) is normally performed by using a slow-wave helix for microwave excitation with a quality factor Q approximately=1. With available microwave sources this low Q factor leads to long microwave pulse lengths for coherent pulse experiments ( pi -pulse duration of about 300 ns for 20 W microwave excitation power). For our zero-field experiments we took advantage of the bridged loop-gap microwave resonator configuration with relatively high Q factor. Without the possibility of tuning the Zeeman energy level splitting as in electron paramagnetic resonance (EPR), in zero-field ODMR the resonator has to cover a wide range of frequencies. We are able to tune our probehead in the range of 1.9-8 GHz with a loaded Q factor of up to 800 by using interchangeable bridged loop-gap resonators of various designs. Thereby, the pulse lengths, compared to the slow-wave helix, could be reduced by nearly one order of magnitude (t/sup pi //sub resonator/=45 ns employing the same microwave power of 20 W). Experimental data are presented for triplet states of photoexcited acridine and benzophenone molecules at different resonance frequencies for their £/sub x/>-£T/sub z/> transitions ( nu =2.472 GHz and nu =5.226 GHz), respectively (17 Refs.) Descriptor(s): magnetic resonance; magnetic resonance spectroscopy; microwave devices; photoexcitation; resonators; spectrometer accessories; triplet state Identifier: interchangeable tuneable bridged loop-gap resonator; pulsed zero-field optically detected magnetic resonance experiments; photoexcited triplet states; ODMR; slow-wave helix; microwave excitation; microwave pulse lengths; coherent pulse experiments; bridged loop-gap microwave resonator; Zeeman energy level splitting; 45 ns; 1.9 to 8 GHz; 20 W; 300 ns; 2.472 GHz Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); A3150 (Excited states of atoms and molecules); A3580 (Atomic and molecular measurements and techniques); A3240 (Magnetic resonance spectra of atoms); B1320 (Waveguide components) Numerical Ind: time 4.5 E-08 s; frequency 1.9 E+09 to 8.0 E+09 Hz; power 2.0 E+01 W; time 3.0 E-07 s; frequency 2.472 E+09 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 588 Copyright: Copyright 1996, IEE Accession No: 5327715 INSPEC Abstract No: A9617-8760I-011 B9609-7510B-029 C9609-7330-032 Author(s): McCallum, S.J.; Alecci, M.; Lurie, D.J. Corp Source: Dept. of Biomed. Phys. & Bioeng., Aberdeen Univ., UK Title: Modification of a whole-body NMR imager into a radio frequency EPR spectrometer suitable for in vivo measurements Source: Measurement Science & Technology, vol.7, no.7 p. 1012-18 ISSN: 0957-0233 CODEN: MSTCEP Publication: UK Language: English Publisher: IOP Publishing Year: July 1996 Copyright No: 0957-0233/96/071012+07$19.50 Treatment: P Practical; X Experimental Record Type: Journal Paper Abstract: We report the modification of a low-field whole-body NMR imager to allow radio frequency EPR spectroscopy. The instrument is designed to give optimum sensitivity for in vivo detection of free radicals. The RF circuit is able to operate over a wide frequency range (240-320 MHz) and is designed to handle input power levels of up to 12.5 W. The EPR resonator is of the loop-gap type suitable for samples up to 400 ml. A remote resonator coupling method has been developed enabling convenient matching adjustment. An automatic frequency control circuit is able to adjust for frequency deviations caused by animal motion. Where possible, existing imager hardware and commercially available instruments have been used. The instrument is controlled from a central computer via an IEEE 488 instrumentation bus. Here we present sensitivity measurements obtained from a variety of large aqueous samples containing nitroxide free radicals. We show that the instrument is suitable for the detection of exogenous free radicals in 200 g rats (31 Refs.) Descriptor(s): automatic frequency control; biomedical equipment; biomedical NMR; EPR spectrometers; medical image processing; peripheral interfaces; physical instrumentation control; spectroscopy computing Identifier: low-field whole-body NMR imager; imager modification; radio frequency EPR spectrometer; in vivo measurements; optimum sensitivity; free radicals detection; wide frequency range; loop-gap type resonator; remote resonator coupling method; matching adjustment; automatic frequency control circuit; computer controlled; IEEE 488 instrumentation bus; large aqueous samples; proton-electron double-resonance imager; 240 to 320 MHz; 12.5 W Class Code: A8760I (Medical magnetic resonance imaging and spectroscopy); A8740 (Biomagnetism); A8770E (Patient diagnostic methods and instrumentation); A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); A0670T (Servo and control devices); B7510B (Radiation and radioactivity applications in biomedicine); B7210B (Automatic test and measurement systems); C7330 (Biology and medical computing); C3110G (Frequency control); C3380D (Control of physical instruments); C7410H (Computerised instrumentation); C3385 (Biological and medical control systems) Numerical Ind: frequency 2.4 E+08 to 3.2 E+08 Hz; power 1.25 E+01 W -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 443 Copyright: Copyright 1996, IEE Accession No: 5298251 INSPEC Abstract No: A9615-0758-004 Author(s): Ghim, B.T.; Rinard, G.A.; Quine, R.W.; Eaton, S.S.; Eaton, G.R. Corp Source: Dept. of Eng. & Chem., Denver Univ., CO, USA Title: Design and fabrication of copper-film loop-gap resonators Source: Journal of Magnetic Resonance, Series A, vol.120, no.1 p. 72-6 ISSN: 1064-1858 CODEN: JMRAE2 Publication: USA Language: English Publisher: Academic Press Year: May 1996 Copyright No: 1064-1858/96/$18.00 Treatment: P Practical Record Type: Journal Paper Abstract: The design, production, and performance of relatively simple, economical, and easy-to-build loop-gap resonators made of copper-clad Teflon (CuFlon) are described. Resonators were built at microwave frequencies between 1 and 9.4 GHz. A C-band continuous wave spectrum, an L-band electron spin-echo signal, and an L-band saturation-recovery signal for irradiated fused silica standard samples are presented (15 Refs.) Descriptor(s): cavity resonators; EPR spectroscopy; paramagnetic resonance; spectrometer accessories; spin echo (EPR) Identifier: Cu-film loop-gap resonators; fabrication; design; production; performance; Cu-clad Teflon; CuFlon; microwave frequencies; C-band continuous wave spectrum; L-band electron spin-echo signal; L-band saturation-recovery signal; irradiated fused silica standard samples; EPR; 1 to 9.4 GHz Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques) Numerical Ind: frequency 1.0 E+09 to 9.4 E+09 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 1017 Copyright: Copyright 1996, IEE Accession No: 5290550 INSPEC Abstract No: A9614-0758-011 Author(s): Plasecki, W.; Froncisz, W.; Hyde, J.S. Corp Source: Biophys. Res. Inst., Med. Coll. of Wisconsin, Milwaukee, WI, USA Title: Bimodal loop-gap resonator Source: Review of Scientific Instruments, vol.67, no.5 p. 1896-904 ISSN: 0034-6748 CODEN: RSINAK Publication: USA Language: English Publisher: AIP Year: May 1996 Copyright No: 0034-6748/96/67(5)/1896/9/$10.00 Treatment: T Theoretical or Mathematical; X Experimental Record Type: Journal Paper Abstract: A bimodal loop-gap resonator for use in electron paramagnetic resonance (EPR) spectroscopy at S band is described. It consists of two identical one-loop-one-gap resonators in coaxial juxtaposition. In one mode, the currents in the two loops are parallel and in the other antiparallel. By introducing additional capacitors between the loops, the frequencies of the two modes can be made to coincide. Details are given concerning variable coupling to each mode, tuning of the resonant frequency of one mode to that of the other, and adjustment of the isolation between modes. An equivalent circuit is given and network analysis carried out both experimentally and theoretically. EPR applications are described including (a) probing of the field distributions with DPPH, (b) continuous wave (cw) EPR with a spin-label line sample, (c) cw electron-electron double resonance (ELDOR), (d) modulation of saturation, and (e) saturation-recovery (SR) EPR. Bloch induction experiments can be performed when the sample extends half way through the structure, but microwave signals induced by M/sub x/ and M/sub y/ components of magnetization cancel when it extends completely through. This latter situation is particularly favorable for SR, modulation of saturation, and ELDOR experiments, which depend on observing M/sub z/ indirectly using a second weak observing microwave source (20 Refs.) Descriptor(s): EPR spectrometers; equivalent circuits; resonators; spectrometer accessories Identifier: bimodal loop-gap resonator; electron paramagnetic resonance spectroscopy; S band; mode coupling; frequency tuning; mode isolation; equivalent circuit; network analysis; DPPH; CW EPR; spin-label line sample; CW ELDOR; saturation modulation; saturation recovery; Bloch induction; microwave signals; magnetization Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 443 Copyright: Copyright 1996, IEE Accession No: 5207229 INSPEC Abstract No: A9608-8780-002 Author(s): Alecci, M.; Nicholson, I.; Lurie, D.J. Corp Source: Dept. of Biomed. Phys. & Bioeng., Aberdeen Univ., UK Title: A novel multiple-tuned radiofrequency loop-gap resonator for use in PEDRI Source: Journal of Magnetic Resonance, Series B, vol.110, no.1 p. 82-6 ISSN: 1064-1866 Publication: USA Language: English Publisher: Academic Press Year: Jan. 1996 Copyright No: 1064-1866/96/$12.00 Treatment: P Practical; X Experimental Record Type: Journal Paper Abstract: We have presented the design of a multiple-tuned RF resonator. The resonant frequencies can be set up to correspond with the EPR resonances of a particular paramagnetic species. The main application of the resonator is in proton-electron double-resonance imaging (PEDRI), where it can be used to irradiate simultaneously multiple EPR transitions of nitroxides. This increases the sensitivity or decreases the applied RF power, the latter being particularly important in biological or human application of the PEDRI technique (22 Refs.) Descriptor(s): biological techniques; biomagnetism; ENDOR; paramagnetic resonance Identifier: multiple-tuned radiofrequency loop-gap resonator; PEDRI; multiple-tuned RF resonator; resonant frequencies; EPR resonances; paramagnetic species; proton-electron double-resonance imaging; multiple EPR transitions; nitroxides; RF power; biological application; human application Class Code: A8780 (Biophysical instrumentation and techniques); A8740 (Biomagnetism); A8760D (Electric and magnetic fields (medical uses)) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 1017 Copyright: Copyright 1996, IEE Accession No: 5193465 INSPEC Abstract No: A9606-0758-002 B9604-1320-007 Author(s): Hirata, H.; Ono, M. Corp Source: Dept. of Electr. Eng. & Comput. Sci., Yamagata Univ., Yonezawa, Japan Title: Resonance frequency estimation of a bridged loop-gap resonator used for magnetic resonance measurements Source: Review of Scientific Instruments, vol.67, no.1 p. 73-8 ISSN: 0034-6748 CODEN: RSINAK Publication: USA Language: English Publisher: AIP Year: Jan. 1996 Copyright No: 0034-6748/96/67(1)/73/6/$6.00 Treatment: P Practical; T Theoretical or Mathematical; X Experimental Record Type: Journal Paper Abstract: This paper presents a method for estimating the resonance frequency of a bridged loop-gap resonator (BLGR). It first describes the structure of the BLGR and its equivalent electrical circuit, and then a procedure for calculating the resonance frequency is revealed. In this procedure, node analysis, which is a circuit theory, is applied to calculate the branch voltages of the equivalent circuit. Finally, this paper reports on the calculations and measurements of the resonance frequency, and the validity of the method for estimating resonance frequency (19 Refs.) Descriptor(s): biomedical equipment; biomedical imaging; capacitance; cavity resonators; EPR spectrometers; EPR spectroscopy; equivalent circuits; frequency estimation; inductance; lumped parameter networks; microwave measurement; spectrometer accessories Identifier: bridged loop-gap resonator; electron paramagnetic resonance measurements; resonance frequency estimation; equivalent electrical circuit; node analysis; branch voltages; in vivo EPR; equivalent lumped circuit; inductances; capacitance Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); A7630 (Electron paramagnetic resonance and relaxation); A8760I (Medical magnetic resonance imaging and spectroscopy); A8770E (Patient diagnostic methods and instrumentation); B1320 (Waveguide components); B1130 (General circuit analysis and synthesis methods); B7510B (Radiation and radioactivity applications in biomedicine); B7310N (Microwave measurement techniques) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 443 Copyright: Copyright 1996, IEE Accession No: 5178151 INSPEC Abstract No: A9605-8780-009 Author(s): Alecci, M.; McCallum, S.J.; Lurie, D.J. Corp Source: Dept. of Biomed. Phys. & Bioeng., Aberdeen Univ., UK Title: Design and optimization of an automatic frequency control system for a radiofrequency electron paramagnetic resonance spectrometer Source: Journal of Magnetic Resonance, Series A, vol.117, no.2 p. 272-7 ISSN: 1064-1858 CODEN: JMRAE2 Publication: USA Language: English Publisher: Academic Press Year: Dec. 1995 Copyright No: 1064-1858/95/$12.00 Treatment: P Practical Record Type: Journal Paper Abstract: We present a simple AFC (automatic frequency control) circuit suitable for EPR spectrometers operating in the RF range. The AFC has been designed: (l) to obtain a good lock to the absorption components of the EPR signal, and (2) to provide frequency lock on the time scale of in vivo experiments. The amount of mixing of the absorption with dispersion EPR components per unit frequency shift has been measured under conditions of high- and low-quality factor of the resonator. In order to simulate in vivo conditions, the AFC has been tested by loading the resonator with large samples of saline solution. We investigated the peak FM voltage that it is necessary to apply at the external DC input of the RF source to obtain the optimal signal-to-noise ratio. All the spectroscopic measurements were made with a homodyne EPR spectrometer equipped with a loop-gap resonator operating at 300 MHz. This apparatus, currently under development in our laboratory, is intended for in vivo EPR spectroscopy and proton-electron double-resonance imaging (17 Refs.) Descriptor(s): automatic frequency control; biological techniques; biomagnetism; EPR spectrometers; magnetic double resonance Identifier: automatic frequency control system optimisation; automatic frequency control system design; automatic frequency control circuit; radiofrequency electron paramagnetic resonance spectrometer; absorption components; EPR signal; frequency lock; in vivo experiments; dispersion EPR components; high-quality factor; low-quality factor; saline solution; resonator loading; peak FM voltage; external DC input; RF source; optimal signal-to-noise ratio; spectroscopic measurements; homodyne EPR spectrometer; loop-gap resonator; proton-electron double-resonance imaging; 300 MHz Class Code: A8780 (Biophysical instrumentation and techniques); A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); A8740 (Biomagnetism) Numerical Ind: frequency 3.0 E+08 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 1017 Copyright: Copyright 1995, IEE Accession No: 5117935 INSPEC Abstract No: A9601-0758-004 Author(s): Pfenninger, S.; Froncisz, W.; Forrer, J.; Luglio, J.; Hyde, J.S. Corp Source: Inst. fur Phys. Chem., Basel Univ., Switzerland Title: General method for adjusting the quality factor of EPR resonators Source: Review of Scientific Instruments, vol.66, no.10 p. 4857-65 ISSN: 0034-6748 CODEN: RSINAK Publication: USA Language: English Year: Oct. 1995 Copyright No: 0034-6748/95/66(10)/4857/9/$6.00 Treatment: T Theoretical or Mathematical; X Experimental Record Type: Journal Paper Abstract: Instrumentation for remote control of the unloaded quality factor, Q/sub 0/, of a loop-gap resonator is described. The value of Q/sub 0/ can be lowered by weak inductive coupling of the resonator to a loop of wire that contains a carbon resistor. Replacement of the resistor by a PIN diode permits remote control. Theoretical analysis and experiments are carried out in a context of electron paramagnetic resonance (EPR) spectroscopy at X band. Equivalent circuits are solved numerically and predicted performance confirmed experimentally. Two applications are demonstrated: (a) superfine control of critical coupling of the incoming transmission line to the resonator in excess of -80 dB, and (b) dynamic Q spoiling for reduction of the dead time after a microwave pulse. Possible degradation of EPR system performance by shot noise from the PIN diode is considered. Scant literature suggests that it is very low, and noise from this source could not be detected experimentally (15 Refs.) Descriptor(s): cavity resonators; EPR spectrometers; equivalent circuits; Q-factor; telecontrol Identifier: EPR resonators; quality factor; remote control; instrumentation; loop-gap resonator; inductive coupling; carbon resistor; PIN diode; electron paramagnetic resonance spectroscopy; X band; equivalent circuits; critical coupling; transmission line; dynamic Q spoiling; dead time; microwave pulse; shot noise Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 1017 Copyright: Copyright 1995, IEE Accession No: 5092450 INSPEC Abstract No: A9523-0758-001 Author(s): Strangeway, R.A.; Mchaourab, H.S.; Luglio, J.R.; Froncisz, W.; Hyde, J.S. Corp Source: Biophys. Res. Inst., Med. Coll. of Wisconsin, Milwaukee, WI, USA Title: A general purpose multiquantum electron paramagnetic resonance spectrometer Source: Review of Scientific Instruments, vol.66, no.9 p. 4516-28 ISSN: 0034-6748 CODEN: RSINAK Publication: USA Language: English Year: Sept. 1995 Copyright No: 0034-6748/95/66(9)/4516/13/$6.00 Treatment: X Experimental Record Type: Journal Paper Abstract: We describe the design, construction, and characterization of an X-band multiquantum electron paramagnetic resonance (MQEPR) microwave bridge, with MQ electron-electron double resonance and MQ electron-nuclear double resonance capabilities. The main feature of the bridge is the use of double-balanced mixers as double sideband modulators to generate multiple irradiation fields with variable frequency separation. The microwave source is a low phase noise Gunn diode oscillator, the frequency of which is translated by a nominal 300+or- Delta f MHz. This approach, called double sideband/fixed filter (DSB/FF), allows the use of fixed bandpass microwave filters to reduce incident spurious products to at least -70 dBc. Each frequency is amplified separately to avoid system-generated intermodulation (IM) sidebands in the incident irradiation. As a result, the dominant source of system intermodulation is the nonlinearity in the receiver system, consisting of a low noise amplifier (LNA) and a double-balanced signal mixer. A detailed analysis of receiver-generated IM products is presented. The use of the loop-gap resonator with a high resonator efficiency parameter, A, and low Q is essential to achieve a balance between microwave power and system IM sidebands. It is shown that even at maximum incident power, the levels of these sidebands can be reduced to 51 dB below the MQEPR response by switching out the LNA. This permits the extension of MQEPR applications into systems where high power is required. The operation modes of the bridge are briefly described. Alternative bridge designs are considered and compared with the DSB/FF design. It is found that the DSB/FF approach gives the best overall performance with greater flexibility and compatibility with multiple operation modes (30 Refs.) Descriptor(s): band-pass filters; bridge instruments; ELDOR; ENDOR; EPR spectrometers; intermodulation; microwave filters Identifier: multiquantum electron paramagnetic resonance spectrometer; X-band MQEPR microwave bridge; electron-electron double resonance; electron-nuclear double resonance; double-balanced mixers; double sideband modulators; Gunn diode oscillator; double sideband/fixed filter; bandpass microwave filters; intermodulation; receiver nonlinearity; low noise amplifier; loop-gap resonator; efficiency parameter; Q factor; 300 MHz Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques) Numerical Ind: frequency 3.0 E+08 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 443 Copyright: Copyright 1995, IEE Accession No: 5074794 INSPEC Abstract No: A9522-0758-009 Author(s): Larsen, F.H.; Daugaard, P.; Jakobsen, H.J.; Nielsen, N.C. Corp Source: Dept. of Chem., Aarhus Univ., Denmark Title: Improving RF field homogeneity in solid-state MAS NMR using a loop-gap resonator Source: Journal of Magnetic Resonance, Series A, vol.115, no.2 p. 283-6 ISSN: 1064-1858 CODEN: JMRAE2 Publication: USA Language: English Year: Aug. 1995 Copyright No: 1064-1858/95/$12.00 Treatment: P Practical; X Experimental Record Type: Journal Paper Abstract: A homogeneous RF field is a prerequisite for optimum performance of most NMR techniques developed with the aim of extracting structural or quantitative information for solids. For example, a well-defined RF field strength is important for (i) accurate manipulation of spin operators through desired coherence-transfer pathways during multiple-pulse, nutation, or spin-lock sequences; (ii) achieving optimum resolution in multiple-pulse decoupling experiments; (iii) a correct interpretation of powder spectra resulting from finite RF pulse excitation; and (iv) quantitative measurements. Despite these facts, only few studies have been concerned with improving RF homogeneity in NMR of solids. In solid-state NMR, self-compensation of RF inhomogeneity using composite pulses is difficult because of inhomogeneous broadening, anisotropic resonance offsets, sample spinning, and short T/sub 2/ values. Therefore, attempts to reduce problems of RF inhomogeneity have addressed the geometries of the sample and RF coil. We explore the utility of a loop-gap (or split-ring) resonator for improving the RF field homogeneity in solid-state magic-angle spinning (MAS) NMR of the common nuclei like /sup 23/Na, /sup 27/Al, /sup 13/C exhibiting resonance frequencies omega /2 pi approximately=100 MHz at 9.4 T. Among the variety of resonator configurations, the loop-gap resonator appears a suitable choice as pointed out by several authors in the context of EPR and large-volume coils for NMR imaging or in vivo spectroscopy. Due to its simple design, it is relatively easy to construct and implement into MAS stators (28 Refs.) Descriptor(s): biological NMR; NMR imaging; spectrometer accessories Identifier: RF field homogeneity; solid-state MAS NMR; loop-gap resonator; homogeneous RF field; NMR imaging; in vivo spectroscopy; large volume coils; split-ring resonator; solid-state magic-angle spinning NMR; /sup 23/Na; /sup 27/Al; /sup 13/C; sample volume; S/N ratio; Na; Al; C Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); A8715M (Interactions with radiations at the biomolecular level); A8740 (Biomagnetism) Chemical Indx: Na/el; Al/el; C/el -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 458 Copyright: Copyright 1995, IEE Accession No: 5046944 INSPEC Abstract No: A9520-0758-002 B9510-7210X-006 Author(s): Sakamoto, Y.; Hirata, H.; Ono, M. Corp Source: Dept. of Electr. Eng. & Comput. Sci., Yamagata Univ., Yonezawa, Japan Title: Design of a multicoupled loop-gap resonator used for pulsed electron paramagnetic resonance measurements Source: IEEE Transactions on Microwave Theory and Techniques, vol.43, no.8 p. 1840-7 ISSN: 0018-9480 CODEN: IETMAB Publication: USA Language: English Year: Aug. 1995 Copyright No: 0018-9480/95/$04.00 Treatment: A Application; P Practical; X Experimental Record Type: Journal Paper Abstract: The purpose of the present paper is to establish a method of design for a multicoupled loop-gap resonator used for pulsed electron paramagnetic resonance measurements. For the design of resonator characteristics, the method has an advantage of a systematic approach without iterative calculations. In this design, the number of loop-gap resonators used is first determined from the pass band required as the specifications of the resonator. To satisfy the specifications, electrical parameters of an equivalent circuit and the dimensions of the resonator are estimated. By the proposed method, a prototype resonator which has the operation frequency of 1.3 GHz is designed and fabricated. For the prototype resonator, the characteristics of the return loss agree with the required ones. As a result, the validity of the design method is experimentally confirmed (12 Refs.) Descriptor(s): EPR spectroscopy; equivalent circuits; microwave spectroscopy; resonators; spectrometer accessories Identifier: multicoupled loop-gap resonator; pulsed electron paramagnetic resonance; pass band specifications; equivalent circuit; electrical parameters; return loss; design method; EPR spectroscopy; 1.3 GHz Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); B7210X (Other instrumentation and measurement systems); B1320 (Waveguide components) Numerical Ind: frequency 1.3 E+09 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 443 Copyright: Copyright 1995, IEE Accession No: 4929850 INSPEC Abstract No: A9510-0758-004 Author(s): Pfenninger, S.; Froncisz, W.; Hyde, J.S. Corp Source: Biophys. Res. Inst., Med. Coll. of Wisconsin, Milwaukee, WI, USA Title: Noise analysis of EPR spectrometers with cryogenic microwave preamplifiers Source: Journal of Magnetic Resonance, Series A, vol.113, no.1 p. 32-9 ISSN: 1064-1858 CODEN: JMRAE2 Publication: USA Language: English Year: March 1995 Copyright No: 1064-1858/95/$6.00 Treatment: X Experimental Record Type: Journal Paper Abstract: Studies are reported on the sensitivity of an EPR spectrometer utilizing a cryogenic preamplifier (0.5 dB noise figure, 35 K equivalent noise temperature). Three cases are considered: (a) resonator matched in a CW experiment, (b) resonator Q spoiled by overcoupling, and (c) resonator matched in pulse experiments. Contributions to the system noise because of losses in the microwave bridge have been determined quantitatively: the equivalent noise temperature of the receiver chain rises from 35 to 100 K. It is suggested that improved system performance can be achieved by cooling major components of the microwave bridge. It is particularly advantageous to cool the load resistor at port 1 of the circulator. Measurements of source noise are reported. This noise contribution becomes increasingly apparent as the system noise is decreased, but can be suppressed by use of loop-gap resonators. Analysis is carried out in a mixed engineering vocabulary of output noise temperature and equivalent noise temperature, which are temperatures referred to the output and input of the circuit, respectively. It is suggested that this is an appropriate analytical approach when there are multiple paths that feed noise to the output of the circuit with different physical temperatures of the input load resistor for each path (20 Refs.) Descriptor(s): EPR spectrometers; EPR spectroscopy; microwave amplifiers; preamplifiers Identifier: noise analysis; EPR spectrometers; cryogenic microwave preamplifiers; noise temperature; matched resonator; CW experiment; resonator Q; overcoupling; microwave bridge losses; receiver chain; load resistor; circulator; source noise measurement; noise contribution; loop-gap resonators; output noise temperature; multiple paths; 35 to 100 K Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); A3330 (Electron paramagnetic resonance and relaxation of molecules); A7630 (Electron paramagnetic resonance and relaxation) Numerical Ind: temperature 3.5 E+01 to 1.0 E+02 K -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 588 Accession No: 4668371 INSPEC Abstract No: A9412-0758-002 Author(s): Koptyug, A.V.; Grishin, Yu.A. Corp Source: Inst. of Chem. Kinetics & Combustion, Acad. of Sci., Novosibirsk, Russia Title: S-band magnetron-based accessory for optical detection of ESR spectra of radiation-induced radical-ion pairs Source: Measurement Science & Technology, vol.5, no.4 p. 363-70 ISSN: 0957-0233 CODEN: MSTCEP Publication: UK Language: English Year: April 1994 Copyright No: 0957-0233/94/040363+08$19.50 Treatment: X Experimental Record Type: Journal Paper Abstract: In the development of the technique of reaction yield detected magnetic resonance (RYDMR), a novel simple accessory for optical detection of ESR (OD ESR), based on the S-band continuous wave magnetron generator is presented. Basic technical requirements for the RYDMR accessories are discussed. The successful use of an S-band magnetron as a microwave source for RYDMR experiments is reported for the first time. Along with the use of a simple loop-gap resonator it permits the studies of both polar and non-polar samples with good sensitivity and field resolution. With the help of this accessory, OD ESR spectra of some new acceptors, acridin and fluorescein, were detected and some new solvents, poly(ethylene glycol) and paraffin-based high-voltage insulator oil, were successfully utilized (33 Refs.) Descriptor(s): magnetic resonance spectroscopy; magnetrons; microwave generation; microwave-optical double resonance; radiation chemistry; spectrometer components and accessories Identifier: S-band magnetron-based accessory; optical detection of ESR spectra; radiation-induced radical-ion pairs; reaction yield detected magnetic resonance; S-band continuous wave magnetron generator; microwave source; RYDMR; loop-gap resonator; nonpolar samples; polar samples; OD ESR spectra; acridin; fluorescein; polyethylene glycol; paraffin-based high-voltage insulator oil Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); A3335H (MODR and PMDR (microwave optical double resonance and phosphorescence microwave double resonance)); A3580 (Atomic and molecular measurements and techniques); A8250 (Photochemistry and radiation chemistry) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 1017 Accession No: 4624293 INSPEC Abstract No: A9408-0758-026 Author(s): Christides, T.; Froncisz, W.; Oles, T.; Hyde, J.S. Corp Source: Biophys. Res. Inst., Med. Coll. of Wisconsin, Milwaukee, WI, USA Title: Probehead with interchangeable loop-gap resonators and rf coils for multifrequency EPR/ENDOR Source: Review of Scientific Instruments, vol.65, no.1 p. 63-7 ISSN: 0034-6748 CODEN: RSINAK Publication: USA Language: English Year: Jan. 1994 Copyright No: 0034-6748/94/65(1)/63/5/$6.00 Treatment: P Practical; X Experimental Record Type: Journal Paper Abstract: A probehead employing interchangeable loop-gap resonators and rf coils for multifrequency EPR/ENDOR spectroscopy from 1 to 10 GHz is described. A precision coupling mechanism allows accurate magnetic coupling of the microwaves to the resonators. The Rexolite support of the resonator acts as a spool for the ENDOR coil. rf fields of 1.0 mT are generated. The coil and resonator can be easily changed to cover the range of 1-10 GHz. Liquid-phase ENDOR spectra of the stable free-radical galvanoxyl and of the spin label TEMPONE (4-oxo-2,2,6,6-tetramethyl-l-piperidine-N-oxyl) dissolved in n-heptane are shown. The ENDOR enhancement for nitrogen from TEMPONE is 15 times larger at 2.3 than at 9.3 GHz due to the rf enhancement (15 Refs.) Descriptor(s): coils; ENDOR; microwave spectra of organic molecules and substances; microwave spectroscopy; nuclear magnetic resonance spectroscopy; paramagnetic resonance of free radicals; spectrometer components and accessories Identifier: interchangeable loop-gap resonators; rf coils; multifrequency EPR/ENDOR; probehead; magnetic coupling; Rexolite support; ENDOR coil; Liquid-phase ENDOR spectra; free-radical galvanoxyl; spin label TEMPONE; 4-oxo-2,2,6,6-tetramethyl-l-piperidine-N-oxyl; n-heptane; 1 mT; 2.3 GHz; 9.3 GHz; 1 to 10 GHz; N Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); A3330 (Electron paramagnetic resonance and relaxation); A3320B (Radiofrequency and microwave spectra) Chemical Indx: N/el Numerical Ind: magnetic flux density 1.0 E-03 T; frequency 2.3 E+09 Hz; frequency 9.3 E+09 Hz; frequency 1.0 E+09 to 1.0 E+10 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 588 Accession No: 4594141 INSPEC Abstract No: A9406-0758-001 B9403-1320-034 Author(s): Piasecki, W.; Froncisz, W. Corp Source: Inst. of Molecular Biol., Jagiellonian Univ., Cracow, Poland Title: Field distributions in loop-gap resonators Source: Measurement Science & Technology, vol.4, no.12 p. 1363-9 ISSN: 0957-0233 CODEN: MSTCEP Publication: UK Language: English Year: Dec. 1993 Copyright No: 0957-0233/93/121363+07$07.50 Treatment: T Theoretical or Mathematical Record Type: Journal Paper Abstract: Maxwell's equations for cylindrical loop-gap resonators used for EPR spectroscopy have been solved with the assumption of the existence of the magnetic z-component only. Resonant structures of the loop-gap resonators with one, two, and four gaps have been investigated. The formulae obtained were used to find the electric and magnetic field distributions numerically. Simple analytical formulae for the magnetic field inhomogeneity were also found and are in good agreement with the experimental observations that the magnetic field homogeneity is improved when the number of gaps is increased. Using the obtained E field distributions a quality factor and signal amplitude for the resonator containing a capillary filled with water were calculated numerically. In spite of neglecting the fringing electric field, the results obtained are in agreement with experiments (14 Refs.) Descriptor(s): cavity resonators; electric fields; electromagnetic field theory; magnetic fields; magnetic resonance spectroscopy; Maxwell equations; paramagnetic resonance Identifier: loop-gap resonators; Maxwell's equations; EPR spectroscopy; resonant structures; magnetic field distributions; electric field distributions; inhomogeneity; E field distributions; quality factor; capillary; fringing electric field Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); A4110F (Steady-state electromagnetic fields; electromagnetic induction); B1320 (Waveguide components); B5100 (Electric and magnetic fields); B5240D (Waveguide and cavity theory) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 443 Accession No: 4567322 INSPEC Abstract No: A9404-0758-011 Author(s): Rinard, G.A.; Quine, R.W.; Eaton, S.S.; Eaton, G.R. Corp Source: Dept. of Eng. & Chem., Denver Univ., CO, USA Title: Microwave coupling structures for spectroscopy Source: Journal of Magnetic Resonance, Series A, vol.105, no.2 p. 137-44 ISSN: 1064-1858 CODEN: JMRAE2 Publication: USA Language: English Year: Nov. 1993 Copyright No: 1064-1858/93/$5.00 Treatment: X Experimental Record Type: Journal Paper Abstract: The coupling of microwave resonators to transmission lines is described for inductive coupling, parallel capacitive coupling, and series capacitive coupling. Equations are presented for the calculation of inductance, capacitance, and resonant frequency of a loop-gap resonator from its physical dimensions. Equations are also given for the parameters of the coupling structure to achieve critical coupling for each of the three coupling methods. Suggestions for practical application of these equations are given (48 Refs.) Descriptor(s): magnetic resonance spectroscopy; paramagnetic resonance; resonators; spectrometer components and accessories Identifier: spectroscopy; microwave resonators; transmission lines; inductive coupling; parallel capacitive coupling; series capacitive coupling; coupling structure; critical coupling Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 443 Accession No: 4567305 INSPEC Abstract No: A9404-8780-001 Author(s): Chzhan, M.; Shteynbuk, M.; Kuppusamy, P.; Zweier, J.L. Corp Source: Dept. of Med., Johns Hopkins Med. Instn., Baltimore, MD, USA Title: An optimized L-band ceramic resonator for EPR imaging of biological samples Source: Journal of Magnetic Resonance, Series A, vol.105, no.1 p. 49-53 ISSN: 1064-1858 CODEN: JMRAE2 Publication: USA Language: English Year: 15 Oct. 1993 Copyright No: 1064-1858/93/$5.00 Treatment: P Practical Record Type: Journal Paper Abstract: The design, engineering parameters, and EPR performance of ceramic re-entrant resonators optimized for L-band EPR imaging of biological samples are reported. Modified equivalent schematics and resonant frequency expressions for the three-loop two-gap re-entrant resonator design are presented. Fabrication techniques and test data for two resonators with a resonant frequency of approximately 1.2 GHz are provided. The unique properties of ceramics enabled the development of a highly stable and highly sensitive re-entrant resonator design of minimum thickness optimally suited for EPR imaging experiments. This resonator yields a signal-to-noise ratio at L band as high as that of X-band cavities for a given-concentration aqueous radical solution of unlimited volume (9 Refs.) Descriptor(s): biological techniques and instruments; paramagnetic resonance Identifier: design parameters; fabrication techniques; optimized L-band ceramic resonator; EPR imaging; biological samples; engineering parameters; EPR performance; resonant frequency expressions; three-loop two-gap re-entrant resonator design; X-band; given-concentration aqueous radical solution; 1.2 GHz Class Code: A8780 (Biophysical instrumentation and techniques); A8740 (Biomagnetism) Numerical Ind: frequency 1.2 E+09 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 1017 Accession No: 4545749 INSPEC Abstract No: A9402-0758-001 Author(s): Hankiewicz, J.H.; Stenland, C.; Kevan, L. Corp Source: Dept. of Chem., Houston Univ., TX, USA Title: Pulsed S-band electron spin resonance spectrometer Source: Review of Scientific Instruments, vol.64, no.10 p. 2850-6 ISSN: 0034-6748 CODEN: RSINAK Publication: USA Language: English Year: Oct. 1993 Copyright No: 0034-6748/93/64(10)/2850/7/$6.00 Treatment: P Practical; X Experimental Record Type: Journal Paper Abstract: A computer-controlled pulsed electron spin resonance spectrometer operating at S-band (2-4 GHz) is described. The instrument is designed for the study of weak interactions between paramagnetic centers and surrounding magnetic nuclei by electron spin-echo modulation techniques. The incorporation of loop-gap resonators gives good sensitivity and allows use over the full octave bandwidth range. Free-induction decay and electron spin-echo signals at room temperature and at liquid-helium temperature are shown in selected sample types. The expected increase of the electron spin-echo modulation depths relative to X band ( approximately 9 GHz) frequencies is demonstrated for proton modulation (23 Refs.) Descriptor(s): cavity resonators; computerised spectroscopy; magnetic resonance spectrometers; spin echo (EPR) Identifier: pulsed S-band electron spin resonance spectrometer; computer-controlled ESR spectrometer; weak interactions; electron spin-echo modulation techniques; loop-gap resonators; octave bandwidth range; free-induction decay; proton modulation; 2 to 4 GHz Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques) Numerical Ind: frequency 2.0 E+09 to 4.0 E+09 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 443 Accession No: 4535380 INSPEC Abstract No: A9401-8780-038 Author(s): Bourg, J.; Krishna, M.C.; Mitchell, J.B.; Tschudin, R.G.; Pohida, T.J.; Friauf, W.S.; Smith, P.D.; Metcalfe, J.; Harrington, F.; Subramanian, S. Corp Source: Div. of Cancer Treatment, Nat. Cancer Inst., Bethesda, MD, USA Title: Radiofrequency FT EPR spectroscopy and imaging Source: Journal of Magnetic Resonance, Series B, vol.102, no.1 p. 112-15 ISSN: 1064-1866 Publication: USA Language: English Year: Aug. 1993 Treatment: P Practical; X Experimental Record Type: Journal Paper Abstract: The study of the role of free radicals in human normal physiology and in pathologic processes is gaining increasing momentum. EPR studies on larger samples such as tissue specimens and perfused organs of small animals were not feasible until the development of spectrometers operating at radiofrequencies and using loop-gap resonators. These spectrometers have permitted the in vivo pharmacology of stable radicals such as nitroxides. However, the detection and monitoring of free radicals at physiological concentrations are not feasible using CW spectrometers since at resonant fields between 100 and 150 G, the Boltzmann factor and therefore the Curie susceptibility are prohibitively low. The authors have constructed a 300 MHz pulsed EPRP spectrometer operating at a resonance field of approximately 107 G (10 Refs.) Descriptor(s): biological techniques and instruments; Fourier transform spectra; molecular biophysics; paramagnetic resonance of free radicals Identifier: radiofrequency FT EPR spectroscopy; imaging; free radicals; human normal physiology; pathologic processes; radiofrequencies; loop-gap resonators; in vivo pharmacology; physiological concentrations; Boltzmann factor; Curie susceptibility; 300 MHz pulsed EPRP spectrometer; 300 MHz; 107 G Class Code: A8780 (Biophysical instrumentation and techniques); A8715M (Interactions with radiations at the biomolecular level) Numerical Ind: frequency 3.0 E+08 Hz; magnetic flux density 1.07 E-02 T -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 215 Accession No: 4444042 INSPEC Abstract No: A9316-8780-020 B9308-7510B-068 Author(s): Anderson, M.E.; Markley, J.L.; Arus, C.; Chobanian, M.C. Corp Source: Wisconsin Univ., Madison, WI, USA Title: A perifusion loop-gap resonator NMR probe for aerobic cell suspensions Source: Magnetic Resonance in Medicine, vol.29, no.4 p. 563-6 ISSN: 0740-3194 CODEN: MRMEEN Publication: USA Language: English Year: April 1993 Copyright No: 0740-3194/93/$3.00 Treatment: P Practical; X Experimental Record Type: Journal Paper Abstract: NMR studies of aerobic cell metabolism require that spectral data of high sensitivity and resolution be acquired from samples maintained under suitable conditions. The loop-gap resonator /sup 31/P NMR probe described here was designed for investigations of highly aerobic-dependent renal proximal tubules in an environment similar to those of conventional incubation flasks. The inherently higher sensitivity of the loop-gap resonator design and associated circuitry made it possible to obtain adequate spectra in short periods of time with small amounts of sample. Cellular physiological properties of perifused aerobic renal proximal tubule cell suspensions in the loop-gap resonator probe were found to be similar to equivalent tissue samples incubated in conventional flasks. Furthermore, the loop-gap perifusion probe was found to provide useful /sup 31/P NMR spectra of the kidney tubule system after acquisition times as short as 3 min (18 Refs.) Descriptor(s): biological NMR; biological techniques and instruments; cellular biophysics; probes; resonators Identifier: cellular physiological properties; acquisition time; perifusion loop-gap resonator NMR probe; aerobic cell suspensions; spectral data; renal proximal tubules; tissue samples; kidney tubule system; 3 min Class Code: A8780 (Biophysical instrumentation and techniques); A8725 (Cellular biophysics); A8740 (Biomagnetism); B7510B (Radiation and radioactivity applications) Numerical Ind: time 1.8 E+02 s -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: Check the catalogs in your library. Libraries that Own Item: 58 Accession No: 4397537 INSPEC Abstract No: A9311-4252-002 B9306-4310-001 Author(s): Saito, H.; Ohta, Y.; Umezu, J. Title: Atomic frequency standards. Development of hydrogen masers Source: Journal of the Communications Research Laboratory, vol.39, no.1 p. 43-51 ISSN: 0914-9260 CODEN: JCRLEX Publication: Japan Language: English Year: March 1992 Treatment: P Practical Record Type: Journal Paper Abstract: The paper gives an outline of the hydrogen masers under development at the Communications Research Laboratory (CRL). Novel techniques are developed to achieve very stable frequency generators. These techniques include a new hydrogen atom energy state selector, two different tuning methods for microwave cavity resonant frequency, improved storage bulb coating methods and other related techniques. Hydrogen masers have been operating continuously since October, 1984. A frequency stability of 1.5*10/sup -15/ (t=2*10/sup 3/ s) is achieved with these masers. A small hydrogen maser with loop-gap resonator and a Q-enhancement technique is also developed. A miniature hydrogen maser development is planned for various applications in the future (29 Refs.) Descriptor(s): cavity resonators; frequency measurement; frequency stability; hydrogen neutral atoms; masers; measurement standards; time measurement Identifier: time measurement; frequency measurement; Communications Research Laboratory; frequency generators; energy state selector; tuning methods; microwave cavity resonant frequency; storage bulb coating methods; frequency stability; loop-gap resonator; Q-enhancement technique; H masers Class Code: A4252 (Masers); A0620H (Measurement standards and calibration); A0630F (Time and frequency measurement); B4310 (Masers); B7320K (Time); B7310G (Frequency); B7130 (Measurement standards and calibration) Chemical Indx: H/el -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 453 Accession No: 4356159 INSPEC Abstract No: A9307-0758-003 Author(s): Tsapin, A.I.; Hyde, J.S.; Froncisz, W. Corp Source: Nat. Biomed. ESR Center, Med. Coll. of Wisconsin, Milwaukee, WI, USA Title: Bimodal loop-gap resonator Source: Journal of Magnetic Resonance, vol.100, no.3 p. 484-90 ISSN: 0022-2364 CODEN: JOMRA4 Publication: USA Language: English Year: Dec. 1992 Copyright No: 0022-2364/92/$5.00 Treatment: T Theoretical or Mathematical Record Type: Journal Paper Abstract: A bimodal loop-gap resonator for electron-electron double resonance at X band is described. Considerable detail is given on frequency tuning; in one of the geometries described, a total tuning range of 500 MHz in the difference of the resonant frequencies of the two modes was achieved. The hypothesis is made that bimodal loop-gap resonators, because of their relatively low Q values, offer opportunities to arrive at structures that are more practical than bimodal cavities for routine EPR use. Data appear to support this hypothesis (16 Refs.) Descriptor(s): ELDOR; magnetic resonance spectrometers; nuclear magnetic resonance spectroscopy; spectrometer components and accessories Identifier: bimodal loop-gap resonator; electron-electron double resonance; X band; frequency tuning; geometries; tuning range; Q values; 500 MHz Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); A3335D (DNMR, ENDOR, ELDOR, Overhauser, INDOR, DNP); A7670K (Electron double resonance (ELDOR)) Numerical Ind: frequency 5.0 E+08 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 1017 Accession No: 4323690 INSPEC Abstract No: A9304-0758-008 Author(s): Alecci, M.; Della Penna, S.; Sotgiu, A.; Testa, L.; Vannucci, I. Corp Source: Dipartimento di Scienze e Tecnologie Biomediche, L'Aquila Univ., Italy Title: Electron paramagnetic resonance spectrometer for three-dimensional in vivo imaging at very low frequency Source: Review of Scientific Instruments, vol.63, no.10, pt.1 p. 4263-70 ISSN: 0034-6748 CODEN: RSINAK Publication: USA Language: English Year: Oct. 1992 Copyright No: 0034-6748/92/104263-08$02.00 Treatment: A Application; P Practical; X Experimental Record Type: Journal Paper Abstract: The authors describe an electron paramagnetic resonance apparatus for spectroscopy and imaging at very low frequency (283 MHz). The bridge operates in a reflection cavity homodyne configuration and can be used on a very broad frequency range. The sample cavity is a one loop-two gap resonator and accepts samples up to 5 cm in diameter and 10 cm long. These sample dimensions make the apparatus suitable for observing living samples such as rats. For the main field and gradients the apparatus uses a newly designed multipolar magnet that can provide the main field and gradients for 2D image reconstruction. The third gradient is obtained by coils mounted in the bore of the magnet. Tests on peroxilamine disulfonate samples have shown micromolar sensitivity. The minimum spatial resolution is limited by the sample linewidth and by the signal/noise. In living samples the toxicity of nitroxide radicals restricts the maximum label concentrations to values of the order of 10/sup -4/ M, and the resolution seems to be limited by sensitivity to fractions of cm/sup 3/ (35 Refs.) Descriptor(s): biological techniques and instruments; image reconstruction; magnetic resonance spectroscopy; paramagnetic resonance Identifier: multipolar magnet; three-dimensional in vivo imaging; bridge; reflection cavity homodyne configuration; sample cavity; one loop-two gap resonator; living samples; rats; 2D image reconstruction; peroxilamine disulfonate samples; micromolar sensitivity; minimum spatial resolution; linewidth; signal/noise; toxicity; nitroxide radicals; maximum label concentrations; 283 MHz; 5 cm; 10 cm Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); A8715M (Interactions with radiations at the biomolecular level); A8740 (Biomagnetism); A8780 (Biophysical instrumentation and techniques) Numerical Ind: frequency 2.83 E+08 Hz; size 5.0 E-02 m; size 1.0 E-01 m -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 1228 Accession No: 4251506 INSPEC Abstract No: A9222-7630R-001 Author(s): Pace, M.D.; Christidis, T.C.; Yin, J.J.; Milliken, J. Corp Source: Nat. Biomed. ESR Center, Med. Coll. of Wisconsin, Milwaukee, WI, USA Title: EPR of a free radical in C/sub 60/: effect of O/sub 2/ Source: Journal of Physical Chemistry, vol.96, no.17 p. 6855-8 ISSN: 0022-3654 CODEN: JPCHAX Publication: USA Language: English Year: 20 Aug. 1992 Copyright No: 0022-3654/92/2096-6855$03.00/0 Treatment: X Experimental Record Type: Journal Paper Abstract: An EPR (electron paramagnetic resonance) signal was detected in C/sub 60/ powder (10/sup -4/ radical-to-C/sub 60/ ratio) and studied by multifrequency (S-, X-, and Q-band) EPR using loop-gap resonators. The signal intensity is dependent on O/sub 2/ as demonstrated by spectra recorded from N/sub 2//O/sub 2/ gas flow experiments, vacuum-evacuated (10/sup -4/ Torr) C/sub 60/ samples, and C/sub 60/ heated in air at 250 degrees C (22 Refs.) Descriptor(s): atomic clusters; carbon; paramagnetic resonance of free radicals; powders; spectral line intensity Identifier: vacuum-evacuated C/sub 60/ samples; fullerene; heat treatment; free radical; EPR; loop-gap resonators; signal intensity; N/sub 2//O/sub 2/ gas flow experiments; 10/sup -4/ torr; 250 degC; O/sub 2/; C/sub 60/ powder; N/sub 2/-O/sub 2/ Class Code: A7630R (Free radicals) Chemical Indx: N2O2/bin N2/bin O2/bin N/bin O/bin; O2/el O/el; C60/el C/el Numerical Ind: pressure 1.3 E-02 Pa; temperature 5.23 E+02 K -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 453 Accession No: 4227086 INSPEC Abstract No: A9219-0758-009 Author(s): Koskinen, M.F.; Metz, K.R. Corp Source: Dept. of Rad., New England Deaconess Hospital & Harvard Med. Sch., Boston, MA, USA Title: The concentric loop-gap resonator-a compact, broadly tunable design for NMR applications Source: Journal of Magnetic Resonance, vol.98, no.3 p. 576-88 ISSN: 0022-2364 CODEN: JOMRA4 Publication: USA Language: English Year: July 1992 Copyright No: 0022-2364/92/$5.00 Treatment: A Application; B Bibliography; X Experimental Record Type: Journal Paper Abstract: A loop-gap resonator design is described for use in NMR applications. Previously reported versions have employed discrete capacitors at the 'gap', which typically yields a very limited tuning range. The resonator described uses one or more concentric tuning cylinders around the inner loop to permit tuning over a range of several hundred megahertz. Construction is straightforward, the Q is high, and the excellent inherent RF field homogeneity of the loop-gap resonator is retained. A simple theoretical model for the operation of this device is presented and verified experimentally. The performance of this concentric loop-gap resonator has proven excellent for /sup 1/H and /sup 19/F NMR imaging and spectroscopy at 4.7 T (53 Refs.) Descriptor(s): magnetic resonance spectrometers; nuclear magnetic resonance spectroscopy; proton magnetic resonance; radiofrequency spectrometers; spectrometer components and accessories Identifier: /sup 1/H NMR; concentric loop-gap resonator; broadly tunable design; NMR applications; concentric tuning cylinders; inherent RF field homogeneity; /sup 19/F NMR; imaging; spectroscopy; 4.7 T Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques) Numerical Ind: magnetic flux density 4.7 E+00 T -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: Check the catalogs in your library. Libraries that Own Item: 28 Accession No: 4210927 INSPEC Abstract No: A9218-0758-009 B9209-1320-021 Author(s): Gromov, I.A.; Orlinskii, S.B.; Rakhmatullin, R.M. Corp Source: Kazan' Univ., USSR Title: 3-cm-band loop-gap resonator for spin-echo spectrometer and laser EPR spectrometer Source: Pribory i Tekhnika Eksperimenta, vol.34, no.5 p. 113-15 ISSN: 0032-8162 CODEN: PRTEAJ Publication: Russia Translated In: Instruments and Experimental Techniques, vol.34, no.5, pt.2 p. 1104-6 ISSN: 0020-4412 CODEN: INETAK Country: USA Language: English Year: Sept.-Oct. 1991; Sept.-Oct. 1991 Copyright No: 0020-4412/91/3405-1104$12.50 Treatment: P Practical; X Experimental Record Type: Journal Paper Abstract: A 3-cm-band single-loop-single-gap reflex resonator for low-temperature studies by electron-spin-echo and magneto-optics methods is described. The resonator which is placed in a nonresonant shield has variable coupling with the waveguide line and provides for tuning. Tests of the resonator show that an optimum electron-spin-echo signal is achieved at a microwave power that is lower by 16 dB than that for a standard rectangular H/sub 102/ resonator, the echo amplitude in this case is increased by 23 dB (11 Refs.) Descriptor(s): cavity resonators; magnetic resonance spectrometers; microwave spectrometers; paramagnetic resonance; spectrometer components and accessories; spin echo (EPR) Identifier: kinetics; loop-gap resonator; spin-echo spectrometer; laser EPR spectrometer; low-temperature studies; electron-spin-echo; magneto-optics; nonresonant shield; variable coupling; waveguide line; 3 cm; 9 GHz Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); B1320 (Waveguide components) Numerical Ind: wavelength 3.0 E-02 m; frequency 9.0 E+09 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Accession No: 4155467 INSPEC Abstract No: A9212-4252-001 B9206-1320-050 Author(s): Opie, D.B.; Schone, H.E.; Hein, M.; Muller, G.; Piel, H.; Schneider, H.-P.; Folen, V.; Frank, A.; Golding, W.M.; Wolf, S. Corp Source: Coll. of William & Mary, Williamsburg, VA, USA Title: A high T/sub c/ superconducting resonator for a compact hydrogen maser Source: Proceedings of the 45th Annual Symposium on Frequency Control 1991 (Cat. No.91CH2965-2) p. 721, 467-76 Publication: USA ISBN: 0879426586 Language: English Publisher: IEEE; New York, NY, USA Sponsor: IEEE Conference Loc: Los Angeles, CA, USA; 29-31 May 1991 Year: 1991 Copyright No: CH2965-2/91/0000-467$01.00 Treatment: X Experimental Record Type: Conference Paper Abstract: The authors describe the development, testing, and evaluation of a superconducting compact hydrogen maser resonator made from electrophoretic Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7- delta / This compact loop-gap resonator, based on a previously suggested maser resonator (H.E. Peters, 1978), is made superconducting using an electrophoretic process developed for the deposition of thick-film polycrystalline high-T/sub c/ superconductors on large nonplanar metallic substrates. At 77 K, cavity quality factors were obtained comparable to those of standard size, room-temperature TE/sub 011/ maser resonators. The fields of the resonators were studied using numerical techniques to determine the dependence of the filling factor and the cavity quality factor on the geometric parameters. This information is used to optimize the cavity design with respect to the effects of thermal radiation on the maser performance at 77 K (16 Refs.) Descriptor(s): barium compounds; cavity resonators; high-temperature superconductors; hydrogen; masers; Q-factor; superconducting devices; yttrium compounds Identifier: high temperature superconductors; compact masers; cavity design optimisation; thermal radiation effects; superconducting resonator; compact loop-gap resonator; electrophoretic process; high-T/sub c/ superconductors; nonplanar metallic substrates; quality factors; filling factor; geometric parameters; maser performance; 77 K; Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7- delta /; H maser Class Code: A4252 (Masers); B1320 (Waveguide components); B3240G (Other superconducting material applications and devices); B3220 (Superconducting materials); B4310 (Masers) Chemical Indx: H/el; Y1Ba2Cu3O/ss Ba2/ss Cu3/ss Ba/ss Cu/ss Y1/ss O/ss Y/ss Numerical Ind: temperature 7.7 E+01 K -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 453 Accession No: 4048216 INSPEC Abstract No: A9202-7670D-001 Author(s): Newton, M.E.; Hyde, J.S. Corp Source: Dept. of Radiol., Med. Coll. of Wisconsin, Milwaukee, WI, USA Title: ENDOR at S-band (2-4 GHz) microwave frequencies Source: Journal of Magnetic Resonance, vol.95, no.1 p. 80-7 ISSN: 0022-2364 CODEN: JOMRA4 Publication: USA Language: English Year: 15 Oct. 1991 Copyright No: 0022-2364/91/$3.00 Treatment: G General Review Record Type: Journal Paper Abstract: Theory, techniques and applications of electron nuclear double resonance (ENDOR) at microwave frequencies lower than X band are considered. Low microwave frequency exploits the hyperfine enhancement effect, resulting in significantly higher effective RF field strengths than in a comparable X-band experiment. The microwave frequency dependences of the magnitude of the CW-ENDOR effect and of ENDOR resolution are discussed. A practical structure for ENDOR at S-band microwave frequencies, incorporating a loop-gap resonator, is described. Experimental results on /sup 14/N ENDOR of the P1 center in diamond and /sup 1/ H matrix ENDOR of gamma -irradiated sucrose are presented (29 Refs.) Descriptor(s): ENDOR; spectral analysis Identifier: S-band; microwave frequencies; electron nuclear double resonance; hyperfine enhancement effect; /sup 1/ H matrix; gamma -irradiated sucrose; 2 to 4 GHz Class Code: A7670D (Electron-nuclear double resonance (ENDOR)); A3335D (DNMR, ENDOR, ELDOR, Overhauser, INDOR, DNP); A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques) Numerical Ind: frequency 2.0 E+09 to 4.0 E+09 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Accession No: 3995227 INSPEC Abstract No: A91133592 B91070360 Author(s): Ohta, Y.; Saito, H.; Umezu, J. Corp Source: Commun. Res. Lab., Minist. of Posts & Telecommun., Koganei, Japan Title: Development of a very small hydrogen maser using a loop-gap resonator Source: Transactions of the Institute of Electronics, Information and Communication Engineers C-I, vol.J74C-I, no.6 p. 222-30 CODEN: DTRCEP Publication: Japan Language: Japanese Year: June 1991 Treatment: P Practical; X Experimental Record Type: Journal Paper Abstract: A small, low-cost hydrogen maser is developed for use with the transportable VLBI (Very Long Baseline Interferometer) system, high speed optical communication system and other systems. The new maser, one-sixth the size of existing units uses a loop-gap cavity resonator as the maser cavity, a smaller selection magnet for the hydrogen atoms and a smaller ion evacuation pump. The resonator quality factor is enhanced with a positive feedback loop for maser oscillation. Resonant frequency, which depends on temperature variation, is stabilized with a newly developed cavity auto-tuning servo system. Preliminary measurements of the maser frequency stability resulted in about 3*10/sup -14/ for an average time of 10/sup 4/ seconds (23 Refs.) Descriptor(s): cavity resonators; frequency stability; hydrogen; masers Identifier: very long baseline interferometer; resonant frequency stabilization; loop-gap resonator; VLBI; high speed optical communication system; maser cavity; selection magnet; ion evacuation pump; resonator quality factor; positive feedback loop; cavity auto-tuning servo system; maser frequency stability; small H maser Class Code: A4252 (Masers); B4310 (Masers) Chemical Indx: H/el -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 442 Accession No: 3949239 INSPEC Abstract No: B91057082 Author(s): Opie, D.; Schone, H.; Hein, M.; Muller, G.; Piel, H.; Wehler, D.; Folen, V.; Wolf, S. Corp Source: Dept. of Phys., Coll. of William & Mary, Williamsburg, VA, USA Title: A superconducting hydrogen maser resonator made from electrophoretic YBa/sub 2/Cu/sub 3/O/sub 7- delta / Source: IEEE Trans. Magn. (USA), IEEE Transactions on Magnetics, vol.27, no.2, pt.4 p. 2944-7 ISSN: 0018-9464 CODEN: IEMGAQ Publication: USA Language: English Sponsor: IEEE Conference: 1990 Applied Superconductivity Conference Conference Loc: Snowmass, CO, USA; 24-28 Sept. 1990 Year: March 1991 Copyright No: 0018-9464/91/0300-2944$01.00 Treatment: P Practical Record Type: Conference Paper; Journal Paper Abstract: The construction and test of three loop-gap resonators which are being prepared for the high-temperature superconductor space experiment (HTSSE) are discussed. The loop-gap electrodes are the lossiest parts of such a resonator. In a first step these electrodes, with a surface of 150 cm/sup 2/, were covered with YBCO. The Q values of the resonators at 77 K ranged between 2.3*10/sup 4/ and 3.1*10/sup 4/ and exceed the minimum requirement for a later maser application. They correspond to a surface resistance between 0.7 and 1.4 m Omega , which is a factor of three to five below the equivalent value of copper. The cavities can be excited in a higher-order mode (HOM) at 4.3 GHz with a field distribution that is still sensitive to the superconducting electrodes. Thus, the experimental requirements for the HTSSE project can be fulfilled (7 Refs.) Descriptor(s): barium compounds; cavity resonators; electrophoretic coatings; high-temperature superconductors; hydrogen; masers; Q-factor; superconducting devices; superconducting thin films; yttrium compounds Identifier: superconducting resonator; SHF; loop-gap resonators; high-temperature superconductor; space experiment; Q values; surface resistance; higher-order mode; superconducting electrodes; HTSSE project; 77 K; 0.7 to 1.4 mohm; 4.3 GHz; electrophoretic YBa/sub 2/Cu/sub 3/O/sub 7- delta /; H maser Class Code: B4310 (Masers); B3240G (Other superconducting material applications and devices); B1320 (Waveguide components) Chemical Indx: H/el; YBa2Cu3O/ss Ba2/ss Cu3/ss Ba/ss Cu/ss O/ss Y/ss Numerical Ind: temperature 7.7 E+01 K; resistance 7.0 E-04 to 1.4 E-03 ohm; frequency 4.3 E+09 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 453 Accession No: 3921552 INSPEC Abstract No: A91094811 Author(s): Brivati, J.A.; Stevens, A.D.; Symons, M.C.R. Corp Source: Dept. of Chem., Leicester Univ., UK Title: A radiofrequency ESR spectrometer for in vivo imaging Source: Journal of Magnetic Resonance, vol.92, no.3 p. 480-9 ISSN: 0022-2364 CODEN: JOMRA4 Publication: USA Language: English Year: May 1991 Copyright No: 0022-2364/91/$3.00 Treatment: P Practical; X Experimental Record Type: Journal Paper Abstract: A radiofrequency ESR spectrometer suitable for in vivo studies is described. The spectrometer utilizes a large loop-gap resonator, 10 cm in diameter and 15 cm in length, with an active volume of about 300 ml. This can be tuned to resonate at exactly 300 MHz for a wide range of samples and enables a fixed frequency source with high spectral purity to be used, minimizing noise demodulation. Automatic tuning, coupling, and phase control systems have been incorporated to compensate for motional artifacts in subsequent experiments using animals. Sensitivity is compared to that obtained using an aqueous cell at X band. For aqueous nitroxides, the minimum detectable concentration is about 2*10/sup -7/ M (sample volume=200 ml, time constant=0.01 s). The effects of physiological salt solution on sensitivity and RF Depth penetration are reported and discussed. Coils for producing magnetic field gradients in three dimensions are also described and preliminary imaging results are shown (20 Refs.) Descriptor(s): biological techniques and instruments; magnetic resonance spectrometers; paramagnetic resonance; radiofrequency spectrometers Identifier: automatic tuning; coils; automatic coupling; automatic phase control; radiofrequency ESR spectrometer; in vivo imaging; large loop-gap resonator; fixed frequency source; animals; aqueous nitroxides; RF Depth penetration; 300 MHz Class Code: A8780 (Biophysical instrumentation and techniques) Numerical Ind: frequency 3.0 E+08 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 453 Accession No: 3903189 INSPEC Abstract No: A91082559 Author(s): Kalyanaraman, B.; Parthasarathy, S.; Joseph, J.; Froncisz, W. Corp Source: Dept. of Radiol., Med., Coll., of Wisconsin, Milwaukee, WI, USA Title: EPR spectra in a loop-gap resonator for a spin-trapped radical from a low-density lipoprotein lipid Source: Journal of Magnetic Resonance, vol.92, no.2 p. 342-7 ISSN: 0022-2364 CODEN: JOMRA4 Publication: USA Language: English Year: April 1991 Copyright No: 0022-2364/91/$3.00 Treatment: X Experimental Record Type: Journal Paper Abstract: An X-band loop-gap resonator has been used to detect the spin adducts derived from oxidation of the low-density lipoprotein. Spin adducts were extracted and concentrated to about 5 mu l and spectra recorded in a loop-gap resonator. The signal-to-noise ratio for the same number of spins is more than eight times greater in the loop-gap resonator than that in the TE/sub 102/ resonator. Biological applications of this methodology are discussed (19 Refs.) Descriptor(s): biological techniques and instruments; free radicals; molecular biophysics; oxidation; paramagnetic resonance of free radicals; proteins; spectrochemical analysis Identifier: EPR spectra; spin-trapped radical; X-band loop-gap resonator; spin adducts; oxidation; signal-to-noise ratio Class Code: A8715M (Interactions with radiations at the biomolecular level); A8780 (Biophysical instrumentation and techniques); A8280D (Electromagnetic radiation spectrometry) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 453 Accession No: 3881649 INSPEC Abstract No: A91064966 Author(s): Mailer, C.; Haas, D.A.; Hustedt, E.J.; Gladden, J.G.; Robinson, B.H. Corp Source: Dept. of Phys., New Brunswick Univ., Fredericton, NB, Canada Title: Low-power electron paramagnetic resonance spin-echo spectroscopy Source: Journal of Magnetic Resonance, vol.91, no.3 p. 475-96 ISSN: 0022-2364 CODEN: JOMRA4 Publication: USA Language: English Year: 15 Feb. 1991 Copyright No: 0022-2364/91/$3.00 Treatment: X Experimental Record Type: Journal Paper Abstract: Electron spin-echo experiments generally require microwave power levels of hundreds of watts to produce the 5-10 G of RF field to generate 90 degrees and 180 degrees pulses in 10 ns. A low-power (i.e. less than 1 W) EPR spectrometer using a loop-gap resonator can generate the full range of time-domain experiments on samples with submicrosecond recovery times; 90 degrees pulses are generated in 40 ns, and relaxation times as short as 22 ns are measured. Appropriate time-domain experiments were performed to independently measure the spin-spin relaxation time, phase memory time, and spin-lattice relaxation time; the results were compared with CW saturation. The spin-spin and spin-lattice relaxation rates do differ by about 5%. The entire CW signal of PADS is reconstructed from a pulse experiment at a single field position. Small differences in linewidths among the three lines were seen in accordance with theory (23 Refs.) Descriptor(s): magnetic resonance spectroscopy; spin echo (EPR) Identifier: signal reconstruction; electron paramagnetic resonance spin-echo spectroscopy; microwave power levels; RF field; EPR spectrometer; loop-gap resonator; time-domain; submicrosecond recovery times; spin-spin relaxation time; phase memory time; spin-lattice relaxation; CW signal; PADS; field position; linewidths; 10 ns; 40 ns; 22 ns Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); A3330 (Electron paramagnetic resonance and relaxation) Numerical Ind: time 1.0 E-08 s; time 4.0 E-08 s; time 2.2 E-08 s -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: Check the catalogs in your library. Libraries that Own Item: 6 Accession No: 3850529 INSPEC Abstract No: A91041274 B91025404 Author(s): Ohta, Y.; Saito, H.; Umezu, J. Title: The development of a small hydrogen maser Source: Review of the Communications Research Laboratory, vol.36, no.180 p. 171-81 ISSN: 0914-9279 CODEN: TSKKED Publication: Japan Language: Japanese Year: Sept. 1990 Treatment: P Practical Record Type: Journal Paper Abstract: Describes a small oscillating hydrogen maser. The maser uses a loop-gap resonator so that the volume of the physics unit is reduced to 1/6 the size of previous hydrogen masers. The Q (quality factor) of the small cavity resonator is electrically enhanced to enable sustained maser oscillation. The long-term frequency stability is improved by a fast cavity tuning servo system. The preliminary frequency stability measurement result is 3*10/sup -14/ for an average time of 10/sup -4/ sec (26 Refs.) Descriptor(s): hydrogen; masers Identifier: hydrogen maser; loop-gap resonator; physics unit; quality factor; cavity resonator; maser oscillation; long-term frequency stability; cavity tuning servo system; frequency stability measurement; average time; H/sub 2/ Class Code: A4252 (Masers); B4310 (Masers) Chemical Indx: H2/el H/el -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 1017 Accession No: 3797822 INSPEC Abstract No: A91014333 Author(s): Forrer, J.; Pfenninger, S.; Eisenegger, J.; Schweiger, A. Corp Source: Lab. fur Phys. Chem., Eidgenossische Tech. Hochschule, Zurich, Switzerland Title: A pulsed ENDOR probehead with the bridged loop-gap resonator: construction and performance Source: Review of Scientific Instruments, vol.61, no.11 p. 3360-7 ISSN: 0034-6748 CODEN: RSINAK Publication: USA Language: English Year: Nov. 1990 Copyright No: 0034-6748/90/113360-08$02.00 Treatment: P Practical; X Experimental Record Type: Journal Paper Abstract: A probehead for pulsed electron-nuclear double resonance (ENDOR) experiments with radio-frequency fields up to 20 mT is introduced. The probehead consists of a bridged loop-gap resonator for X-band microwave frequencies surrounded by a solenoidal RF coil that generates the radio-frequency field, and serves as microwave radiation shield. A broad band and a tuned circuit for pulsed. ENDOR experiments between 1-200 and 1.5-26 MHz, respectively, are described. Details of the probehead design and characteristics of the RF circuits are given. The performance of the probehead is demonstrated by pulsed ENDOR spectra in solids and liquids between 8 and 150 MHz and by an ENDOR experiment that requires a stepping of the static magnetic field strength (46 Refs.) Descriptor(s): ENDOR; microwave spectroscopy; nuclear magnetic resonance spectroscopy; resonators; spectrometer components and accessories Identifier: RF fields; pulsed ENDOR probehead; bridged loop-gap resonator; electron-nuclear double resonance; X-band microwave frequencies; solenoidal RF coil; microwave radiation shield; pulsed ENDOR spectra; static magnetic field strength; 20 mT; 1 to 200 MHz; 1.5 to 26 MHz Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques) Numerical Ind: magnetic flux density 2.0 E-02 T; frequency 1.0 E+06 to 2.0 E+08 Hz; frequency 1.5 E+06 to 2.6 E+07 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 453 Accession No: 3681628 INSPEC Abstract No: A90106516 Author(s): Dirksen, P.; Disselhorst, J.A.J.M.; van der Meer, H.; Wenckebach, W.T. Corp Source: Kamerlingh Onnes & Huygens Lab., Leiden, Netherlands Title: A loop-gap resonator for microwave-induced optical nuclear polarization, electron spin-echo experiments, and dynamic nuclear polarization Source: Journal of Magnetic Resonance, vol.87, no.3 p. 516-22 ISSN: 0022-2364 CODEN: JOMRA4 Publication: USA Language: English Year: May 1990 Copyright No: 0022-2364/90/$3.00 Treatment: X Experimental Record Type: Journal Paper Abstract: A special double loop-gap resonator for CW and pulsed EPR experiments at X band is presented. It allows for simultaneous optical access, high uniaxial pressure on the sample, and NMR and EPR experiments at liquid helium temperatures. It is used for microwave-induced optical nuclear polarization in semiconductors (7 Refs.) Descriptor(s): dynamic nuclear polarisation; magnetic resonance spectroscopy; microwave-optical double resonance; nuclear magnetic resonance spectroscopy; semiconductors; spectrometer components and accessories; spin echo (EPR) Identifier: CW EPR experiments; microwave-induced optical nuclear polarization; electron spin-echo experiments; dynamic nuclear polarization; double loop-gap resonator; pulsed EPR experiments; X band; high uniaxial pressure; semiconductors; 4.2 K Class Code: A7670E (Dynamical nuclear polarization); A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); A7670H (Optical double magnetic resonance (ODMR)); A7630 (Electron paramagnetic resonance and relaxation) Numerical Ind: temperature 4.2 E+00 K -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 215 Accession No: 3643446 INSPEC Abstract No: A90085103 B90040938 Author(s): Murphy, M.K.; Fernandez, E.J.; Clark, D.S. Corp Source: Dept. of Chem. Eng., California Univ., Berkeley, CA, USA Title: A comparison of three radiofrequency coils for NMR studies of conductive samples Source: Magnetic Resonance in Medicine, vol.12, no.3 p. 382-9 ISSN: 0740-3194 CODEN: MRMEEN Publication: USA Language: English Year: Dec. 1989 Copyright No: 0740-3194/89/$3.00 Treatment: P Practical Record Type: Journal Paper Abstract: Three RF coil designs of equal volume (approximately 15 ml) were compared using conductive samples. Magnetic loss into the sample was the dominant noise source. At physiological conductivity the sensitivity of the horizontally aligned solenoid and loop-gap resonator was only 1.3+or-0.2 times that of the vertically aligned slotted tube resonator (19 Refs.) Descriptor(s): biological techniques and instruments; coils; nuclear magnetic resonance spectroscopy Identifier: magnetic loss; metabolites; NMR studies; conductive samples; RF coil designs; noise source; physiological conductivity; horizontally aligned solenoid; loop-gap resonator; vertically aligned slotted tube resonator Class Code: A8780 (Biophysical instrumentation and techniques); A8740 (Biomagnetism); B7510B (Radiation and radioactivity applications) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Accession No: 3567239 INSPEC Abstract No: A90031232 Editor: Hoff, A.J. Title: Advanced EPR, applications in biology and biochemistry Source: p. xxiii+918 Publication: Netherlands ISBN: 044488050x Language: English Publisher: Elsevier; Amsterdam, Netherlands Year: 1989 Record Type: Book Abstract: This book reports new developments in EPR and ENDOR with emphasis on applications in biology and biochemistry. The topics covered are: electron spin echo envelope modulation (ESEEM) and linear electric field effect of metalloproteins and model compounds; ESEEM of disordered systems; multifrequency ESEEM; resolution enhancement in time domain analysis of ESEEM; two-dimensional and Fourier transform EPR; pulsed EPR on disordered systems; loop gap resonators; time-resolved EPR; millimetre wave EPR; transient EPR of photoinduced electronic spin states in rigid matrices; polarised EPR; liquid state ENDOR and TRIPLE resonance; ENDOR of haemoglobin interactions and metalloenzymes; pulsed ENDOR; ENDOR amplitude spectroscopy; ODMR of triplet states; RYDMR; spin label spectra; g-strain Descriptor(s): biological techniques and instruments; ENDOR; magnetic resonance spectroscopy; paramagnetic resonance; spin echo (EPR) Identifier: advanced EPR; two dimensional EPR; ENDOR; biology; biochemistry; electron spin echo envelope modulation; linear electric field effect; metalloproteins; model compounds; disordered systems; multifrequency; resolution enhancement; time domain analysis; Fourier transform EPR; pulsed EPR; loop gap resonators; time-resolved EPR; millimetre wave EPR; transient EPR; photoinduced electronic spin states; rigid matrices; polarised EPR; liquid state ENDOR; TRIPLE resonance; haemoglobin interactions; metalloenzymes; pulsed ENDOR; ENDOR amplitude spectroscopy; ODMR; triplet states; RYDMR; spin label spectra; g-strain Class Code: A0130E (Monographs, and collections); A8780 (Biophysical instrumentation and techniques); A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); A8715M (Interactions with radiations at the biomolecular level) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 550 Accession No: 3559344 INSPEC Abstract No: A90036811 Author(s): Altenbach, C.; Froncisz, W.; Hyde, J.S.; Hubbell, W.L. Corp Source: Jules Stein Eye Inst., California Univ., Los Angeles, CA, USA Title: Conformation of spin-labeled melittin at membrane surfaces investigated by pulse saturation recovery and continuous wave power saturation electron paramagnetic resonance Source: Biophysical Journal, vol.56, no.6 p. 1183-91 ISSN: 0006-3495 CODEN: BIOJAU Publication: USA Language: English Year: Dec. 1989 Copyright No: 0006-3495/89/12/1183/09$2.00 Treatment: X Experimental Record Type: Journal Paper Abstract: Melittin spin-labeled specifically with a nitroxide at positions 7, 21, 23, or the amino terminus was bound to phospholipid membranes and the exposure of the spin label to the aqueous phase was investigated by measurement of Heisenberg exchange with chromium oxalate in the solution. The exchange frequency was determined by saturation recovery electron paramagnetic resonance (EPR) using a loop-gap resonator. This method allows use of very low concentrations (<1 mM) of chromium oxalate compared with conventional measurements of EPR line broadening (typically 50 mM), thus avoiding problems associated with high metal ion concentration. Differences in exchange frequency between the various positions were also estimated by continuous wave power saturation methods. In either approach, the spin label at lysine 7 was found to be the most exposed to chromium oxalate whereas that at lysine 23 was found to be the least exposed (44 Refs.) Descriptor(s): molecular biophysics; organic compounds; organic molecule configurations Identifier: CW power saturation EPR; pulse saturation recovery EPR; molecular conformation; spin-labeled melittin; membrane surfaces; phospholipid membranes; aqueous phase; Heisenberg exchange; electron paramagnetic resonance; loop-gap resonator; metal ion concentration; lysine 23 Class Code: A8715B (Structure, configuration, conformation, and active sites at the biomolecular level); A8715M (Interactions with radiations at the biomolecular level) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 453 Accession No: 3539127 INSPEC Abstract No: A90017435 B90007141 Author(s): Ichikawa, T.; Yoshida, H.; Westerling, J. Corp Source: Fac. of Eng., Hokkaido Univ., Sapporo, Japan Title: Coupling structure for the loop-gap resonator Source: Journal of Magnetic Resonance, vol.85, no.1 p. 132-6 ISSN: 0022-2364 CODEN: JOMRA4 Publication: USA Language: English Year: 15 Oct. 1989 Copyright No: 0022-2364/89/$3.00 Treatment: P Practical; X Experimental Record Type: Journal Paper Abstract: The loop-gap resonator is a lumped-circuit microwave resonator which offers a number of advantages in electron spin resonance spectroscopy including electron-electron double resonance, electron-nuclear double resonance, and pulsed ESR measurement. Among these are the large RF magnetic field per incident microwave power, high filling factor, and low quality factor Q. Microwave coupling to the loop-gap resonator is usually achieved by placing the resonator in a nonresonant RF shield and using an inductive loop at the end of a rigid coaxial cable. Critical coupling is achieved by adjusting the distance between the inductive loop and the resonator. The advantage of this coupling arrangement is its mechanical compactness. The resonator and the coupler are small enough to perform temperature-controlled experiments by inserting the resonator in a gas-flow cryostat. This coupling arrangement has two disadvantages. One is the loss of microwave power in the coaxial cable. The loss is typically 3 dB, which diminishes the available RF field in the resonator. The other is mechanical instability of the coupling arrangement. The coupling is so sensitive to the location of the inductive loop that it is sometimes difficult to attain critical coupling. One way to overcome these disadvantages is to use a coupling device which is composed of a waveguide. The authors have found that the loop-gap resonator can be capacitively and inductively coupled to a waveguide by using an iris and a Gordon coupler. The capacitive coupling is attained by using a nonresonant rectangular shield (14 Refs.) Descriptor(s): cavity resonators; magnetic resonance spectrometers; paramagnetic resonance; spectrometer components and accessories Identifier: microwave coupling; critical coupling; loop-gap resonator; lumped-circuit microwave resonator; electron spin resonance spectroscopy; electron-electron double resonance; electron-nuclear double resonance; pulsed ESR; RF magnetic field; incident microwave power; filling factor; quality factor; RF shield; inductive loop; rigid coaxial cable; mechanical compactness; temperature-controlled experiments; gas-flow cryostat; microwave power; coaxial cable; loss; RF field; inductive loop; waveguide; iris; Gordon coupler; capacitive coupling; nonresonant rectangular shield Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); B1320 (Waveguide components) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 429 Accession No: 3511650 INSPEC Abstract No: A90003974 Author(s): Ishida, S.; Kumashiro, H.; Tsuchihashi, N.; Ogata, T.; Ono, M.; Kamada, H.; Yoshida, E. Corp Source: Dept. of Neuropsychiatry, Fukushima Med. Coll., Japan Title: In vivo analysis of nitroxide radicals injected into small animals by L-band ESR technique Source: Physics in Medicine and Biology, vol.34, no.9 p. 1317-23 ISSN: 0031-9155 CODEN: PHMBA7 Publication: UK Language: English Year: Sept. 1989 Copyright No: 0031-9155/89/091317+07$02.50 Treatment: P Practical; X Experimental Record Type: Journal Paper Abstract: The authors have developed an L-band ESR system with a loop-gap resonator and using this system they have successfully performed in vivo ESR measurements of nitroxides administered to rats. This system is quite suitable for direct observation of free radicals in living animals even though exogenous ones are described here (13 Refs.) Descriptor(s): biological techniques and instruments; organic compounds; paramagnetic resonance Identifier: exogenous radicals; biophysical research technique; small animals; L-band ESR technique; loop-gap resonator; rats; free radicals; living animals Class Code: A8780 (Biophysical instrumentation and techniques) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 453 Accession No: 3478649 INSPEC Abstract No: A89124404 Author(s): Crepeau, R.H.; Dulcic, A.; Gorcester, J.; Saarinen, T.R.; Freed, J.H. Corp Source: Baker Lab. of Chem., Cornell Univ., Ithaca, NY, USA Title: Composite pulses in time-domain ESR Source: Journal of Magnetic Resonance, vol.84, no.1 p. 184-90 ISSN: 0022-2364 CODEN: JOMRA4 Publication: USA Language: English Year: Aug. 1989 Copyright No: 0022-2364/89/$3.00 Treatment: T Theoretical or Mathematical Record Type: Journal Paper Abstract: The authors demonstrate that composite pulses can be successfully employed in time-domain ESR to enhance spectral coverage. Also, they show that this approach, in conjunction with a specially designed BLGR, can now provide effective (although nonuniform) coverage over at least a 200 MHz spectrum. Considerable further improvement in coverage can be expected from these simple phase-alternating composite pulses based upon the theoretical predictions with careful choice of resonator Q and (perhaps) improved switching times (16 Refs.) Descriptor(s): magnetic resonance spectroscopy; paramagnetic resonance; resonators; spectrometer components and accessories Identifier: bridged loop-gap resonator; composite pulses; time-domain ESR; spectral coverage; specially designed BLGR; phase-alternating composite pulses; resonator; improved switching times Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 458 Accession No: 3432810 INSPEC Abstract No: B89054132 Author(s): Mehdizadeh, M.; Ishii, T.K. Corp Source: Dept. of Electr. Eng. & Comput. Sci., Marquette Univ., Milwaukee, WI, USA Title: Electromagnetic field analysis and calculation of the resonance characteristics of the loop-gap resonator Source: IEEE Transactions on Microwave Theory and Techniques, vol.37, no.7 p. 1113-18 ISSN: 0018-9480 CODEN: IETMAB Publication: USA Language: English Year: July 1989 Copyright No: 0018-9480/89/0700-1113$01.00 Treatment: T Theoretical or Mathematical Record Type: Journal Paper Abstract: The electromagnetic field configuration of the loop-gap resonator is analyzed, and expressions for field distributions are derived. The method involves solving Maxwell's equations for the boundary conditions and matching the internal magnetic fields of the resonator to the evanescent fringing fields by a numerical fitting method. The expressions derived from this analysis are used in the derivation of equations for the resonant frequency and the quality factor of the resonator. The computed results are in good agreement with the measured values for resonant frequency and quality factors (10 Refs.) Descriptor(s): boundary-value problems; cavity resonators; electromagnetic fields Identifier: resonance characteristics; loop-gap resonator; electromagnetic field configuration; field distributions; Maxwell's equations; boundary conditions; internal magnetic fields; evanescent fringing fields; numerical fitting; quality factor Class Code: B1320 (Waveguide components) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 1017 Accession No: 3404667 INSPEC Abstract No: A89079548 Author(s): Oles, T.; Hyde, J.S.; Froncisz, W. Corp Source: Nat. Biomed. ESR Center, Med. Coll. of Wisconsin, Milwaukee, WI, USA Title: Gordon coupler for K-band EPR loop gap resonator Source: Review of Scientific Instruments, vol.60, no.3 p. 389-91 ISSN: 0034-6748 CODEN: RSINAK Publication: USA Language: English Year: March 1989 Copyright No: 0034-6748/89/030389-03$01.30 Treatment: P Practical Record Type: Journal Paper Abstract: A Gordon-type coupler is described for a three-loop two-gap resonator for electron paramagnetic resonance (EPR) spectroscopy at 19 GHz. Dimensions and microwave characterization of the resonator also are provided. The resonator is particularly intended for aqueous samples in 'flat cell' geometry. The range of coupling is sufficient to match flat cells of optimum thickness for best sensitivity. The coupling is based on overlap of evanescent fields of the loop gap resonator and transmission line (20 Refs.) Descriptor(s): magnetic resonance spectroscopy; microwave spectroscopy; paramagnetic resonance; resonators; spectrometer components and accessories Identifier: magnetic resonance spectroscopy; flat cell geometry; Gordon-type coupler; three-loop two-gap resonator; electron paramagnetic resonance; coupling; overlap of evanescent fields; 19 GHz Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques) Numerical Ind: frequency 1.9 E+10 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 453 Accession No: 3402618 INSPEC Abstract No: A89079534 Author(s): Hyde, J.S.; Froncisz, W.; Oles, T. Corp Source: Nat. Biomed. ESR Center, Med. Coll. of Wisconsin, Milwaukee, WI, USA Title: Multipurpose loop-gap resonator Source: Journal of Magnetic Resonance, vol.82, no.2 p. 223-30 ISSN: 0022-2364 CODEN: JOMRA4 Publication: USA Language: English Year: April 1989 Copyright No: 0022-2364/89/$3.00 Treatment: P Practical; X Experimental Record Type: Journal Paper Abstract: A three-loop-two-gap resonator is described that has properties that are similar to the widely used X-band rectangular TE/sub 102/ multipurpose cavity. Both structures accommodate the same cavity accessories interchangeably: variable temperature Dewar insert, liquid nitrogen Dewar, electrochemical cell, tissue cell, and flat cell. However, optimum performance with the loop-gap resonator (LGR) is achieved with 1 mm flat cells rather than 0.4 mm cells used in the cavity. The lower Q of the LGR decreases the demodulation of phase noise when tuned to the dispersion. The geometry is flexible and it is suggested that it can serve as a convenient general purpose resonator for ESR spectroscopy (9 Refs.) Descriptor(s): magnetic resonance spectroscopy; spectrometer components and accessories Identifier: multipurpose resonator; three-loop-two-gap resonator; cavity accessories; variable temperature Dewar insert; electrochemical cell; tissue cell; flat cell; demodulation; phase noise; geometry; ESR spectroscopy; liquid N/sub 2/ Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques) Chemical Indx: N2/el N/el -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 453 Accession No: 3402606 INSPEC Abstract No: A89083260 Author(s): Lersch, W.; Lendzian, F.; Lang, E.; Feick, R.; Mobius, K.; Michel-Beyerle, M.E. Corp Source: Inst. fur Phys. & Theor. Chem. Tech. Univ. Munchen, Garching, West Germany Title: High-power RYDMR with a loop-gap resonator Source: Journal of Magnetic Resonance, vol.82, no.1 p. 143-9 ISSN: 0022-2364 CODEN: JOMRA4 Publication: USA Language: English Year: March 1989 Copyright No: 0022-2364/89/$3.00 Treatment: X Experimental Record Type: Journal Paper Abstract: Standard electron spin resonance spectrometers normally employ microwave cavities as the resonance structure. As an alternative, loop-gap resonators have been introduced to electron spin resonance spectroscopy and various modifications of the original construction are described in the literature. By its high filling factor, its excellent field homogeneity, and its favorable conversion of microwave power into microwave field strength the loop-gap resonator is especially suited for high-power electron spin resonance investigations of dilute biological samples. The authors applied the loop-gap resonator to record the Reaction Yield Detected Magnetic Resonance (RYDMR) signal from photosynthetic bacterial reaction centers up to microwave field strengths B/sub 1/ of more than 3 mT in the rotating frame. Applied to bacterial reaction centers, RYDMR is an excellent method to characterize the spin-dependent recombination dynamics of the first light induced radical ion pair state consisting of a bacteriochlorophyll dimer cation radical (BChl/sub 2//sup +./) and a bacteriopheophytin anion radical (BPh/sup -./) (21 Refs.) Descriptor(s): biological techniques and instruments; magnetic resonance spectroscopy; molecular biophysics; paramagnetic resonance of free radicals; spectrometer components and accessories Identifier: RYDMR; loop-gap resonator; resonance structure; electron spin resonance spectroscopy; field homogeneity; dilute biological samples; Reaction Yield Detected Magnetic Resonance; photosynthetic bacterial reaction centers; spin-dependent recombination dynamics; light induced radical ion pair state; bacteriochlorophyll dimer cation radical; bacteriopheophytin anion radical Class Code: A8780 (Biophysical instrumentation and techniques); A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); A8715M (Interactions with radiations at the biomolecular level) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 453 Accession No: 3402602 INSPEC Abstract No: A89083259 Author(s): Froncisz, W.; Oles, T.; Hyde, J.S. Corp Source: Dept. of Biophys., Inst. of Molecular Biol., Jagiellonian Univ., Krakow, Poland Title: Murine L-band ESR loop-gap resonator Source: Journal of Magnetic Resonance, vol.82, no.1 p. 109-14 ISSN: 0022-2364 CODEN: JOMRA4 Publication: USA Language: English Year: March 1989 Copyright No: 0022-2364/89/$3.00 Treatment: X Experimental Record Type: Journal Paper Abstract: Construction details, engineering characterization, and spectroscopic performance are given for an L-band (1.1 GHz) loop-gap resonator intended for in vivo electron spin resonance experiments on mice. The active diameter is 2.5 cm and the length is 3 cm (12 Refs.) Descriptor(s): biological techniques and instruments; paramagnetic resonance; resonators; spectrometer components and accessories Identifier: construction details; ESR; engineering characterization; spectroscopic performance; L-band; loop-gap resonator; in vivo electron spin resonance experiments; mice; 2.5 cm; 3 cm; 1.1 GHz Class Code: A8780 (Biophysical instrumentation and techniques); A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques) Numerical Ind: size 2.5 E-02 m; size 3.0 E-02 m; frequency 1.1 E+09 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 1017 Accession No: 3285491 INSPEC Abstract No: A89011208 C89006715 Author(s): Hyde, J.S.; Gajdzinski, J. Corp Source: Dept. of Radiol., Med. Coll. of Wisconsin, Milwaukee, WI, USA Title: EPR automatic frequency control circuit with field effect transistor (FET) microwave amplification Source: Review of Scientific Instruments, vol.59, no.8, pt.1 p. 1352-6 ISSN: 0034-6748 CODEN: RSINAK Publication: USA Language: English Year: Aug. 1988 Copyright No: 0034-6748/88/081352-05$01.30 Treatment: P Practical Record Type: Journal Paper Abstract: An electron-paramagnetic-resonance (EPR) reference-arm microwave bridge is described that incorporates a FET microwave amplifier and a balanced quadrature mixer. An automatic frequency control (AFC) circuit is described that employs 70-kHz frequency modulation of the oscillator. AFC feedback is based on formation of the sum of squares of the I and Q outputs of the mixer using analog devices. The resulting AFC circuit is independent of the phase angle alpha of the reference-arm microwave voltage with respect to the signal-arm microwave voltage at the mixer. An L-band bridge is described that incorporates the circuit. Good AFC lock was obtained from 1 mu W to 100 mW of incident power independent of alpha using a loop-gap resonator of Q=500 (3 Refs.) Descriptor(s): automatic frequency control; bridge circuits; field effect transistors; magnetic resonance spectroscopy; microwave amplifiers; paramagnetic resonance; physical instrumentation control Identifier: microwave amplification; electron-paramagnetic-resonance; reference-arm microwave bridge; FET microwave amplifier; balanced quadrature mixer; automatic frequency control; feedback; reference-arm microwave voltage; signal-arm microwave voltage; L-band bridge; loop-gap resonator; 70 kHz; 1 muW to 100 mW Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); A0670T (Servo and control devices); C3380D (Physical instruments); C3110G (Frequency) Numerical Ind: frequency 7.0 E+04 Hz; power 1.0 E-06 to 1.0 E-01 W -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 609 Accession No: 3234102 INSPEC Abstract No: A88127119 Author(s): Chen, K.Y.; Liu, W.; Feng, Y.H.; Li, W.X. Corp Source: Dept. of Electron. Sci., Nankai Univ., Tianjin, China Title: Optimum design and performance of a 1.4 GHz loop-gap resonator used in an ESR spectrometer Source: Journal of Physics E (Scientific Instruments), vol.21, no.7 p. 660-2 ISSN: 0022-3735 CODEN: JPSIAE Publication: UK Translated In: A07 Language: English Year: July 1988 Copyright No: 0022-3735/88/070660+03$02.50 Treatment: T Theoretical or Mathematical Record Type: Journal Paper Abstract: A more accurate design equation for the resonant frequency of the loop gap resonator has been derived on the basis of equivalent circuit theory. An expression for the quality factor Q is proposed, and the optimum geometrical sizes of the resonator for high Q values have been obtained by the use of a microcomputer. The difference between the theoretical frequency and the practical one is within 7%, and a high Q value of 1800 has been measured for the prototype with optimum sizes (6 Refs.) Descriptor(s): equivalent circuits; magnetic resonance spectrometers; microwave spectrometers Identifier: optimum design; loop-gap resonator; ESR spectrometer; resonant frequency; equivalent circuit theory; quality factor; 1.4 GHz Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques) Numerical Ind: frequency 1.4 E+09 Hz -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 1017 Accession No: 3195417 INSPEC Abstract No: A88101389 B88050318 Author(s): Pfenninger, S.; Forrer, J.; Schweiger, A. Corp Source: Lab. fur Phys. Chem., Eidgenossische Tech. Hochschule, Zurich, Switzerland Title: Bridged loop-gap resonator: a resonant structure for pulsed ESR transparent to high-frequency radiation Source: Review of Scientific Instruments, vol.59, no.5 p. 752-60 ISSN: 0034-6748 CODEN: RSINAK Publication: USA Translated In: A11 Language: English Year: May 1988 Copyright No: 0034-6748/88/050752-09$01.30 Treatment: A Application; T Theoretical or Mathematical; X Experimental Record Type: Journal Paper Abstract: A new and inexpensive X-band resonator structure for pulsed electron-spin resonance and electron-nuclear-double-resonance applications is introduced. The resonator consists of a bridged loop structure and is distinguished by a good reproducibility and reliability. It has a high filling factor and an adjustable Q value and is transparent to radio frequency fields with an upper limit >100 MHz. The inner diameter of 5 mm allows convenient sample access of standard 4-mm quartz tubes in the temperature range between 4 and 300 K. Numerical computations of the resonant frequencies, the Q values, and the three-dimensional distributions of the electromagnetic fields are presented. They are based on a discretization method for the solution of Maxwell's equations and include all dielectric elements of the resonator structure. The field homogeneity in the sample area and the influence of the dimensions and the thickness of the metallic layers on field intensity, quality factor, and resonant frequency are determined experimentally. The performance of the resonator is demonstrated by a novel field-swept echo-induced electron-spin-resonance experiment with jumping magnetic field vectors (38 Refs.) Descriptor(s): cavity resonators; magnetic resonance spectroscopy; microwave spectroscopy; paramagnetic resonance Identifier: Maxwell equations; microwave spectroscopy; magnetic resonance spectroscopy; resonant structure; pulsed ESR; X-band resonator; electron-nuclear-double-resonance applications; bridged loop structure; reproducibility; reliability; three-dimensional distributions; electromagnetic fields; dielectric elements; field homogeneity; dimensions; thickness; field intensity; quality factor; resonant frequency; field-swept echo-induced electron-spin-resonance experiment; jumping magnetic field vectors; 100 MHz; 5 mm; 4 mm; 4 to 300 K Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques); B1320 (Waveguide components) Numerical Ind: frequency 1.0 E+08 Hz; size 5.0 E-03 m; size 4.0 E-03 m; temperature 4.0 E+00 to 3.0 E+02 K -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Accession No: 3118989 INSPEC Abstract No: B88028744 Author(s): Howson, C.D.; Kazeminejad, S.; Howson, D.P. Title: A comparison of possible duplexer designs for TACS system mobile units Source: Land Mobile Radio. Fourth International Conference (Publ. No.78) p. 258, 163-6 Publication: UK Translated In: B02 ISBN: 0903748754 Language: English Publisher: IERE; London, UK Conference Loc: Coventry, UK; 15-17 Dec. 1987 Year: 1987 Treatment: P Practical Record Type: Conference Paper Abstract: A variety of different resonator designs have been either proposed or are in use in TACS mobile radios. Ceramic-filled coaxial resonators of different patterns, and dielectric resonators are examined, together with strip line designs. Loop-gap and SAW resonators also have potential for this use, and will be included in the survey. Various duplexer configurations using these resonators will be compared, in terms of performance, stability, and ease of manufacture, size and costs (13 Refs.) Descriptor(s): mobile radio systems; resonators Identifier: loop-gap; duplexer; TACS system mobile units; mobile radios; coaxial resonators; dielectric resonators; strip line; SAW; performance; stability; manufacture; size; costs Class Code: B1320 (Waveguide components); B6250F (Mobile radio systems) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 453 Accession No: 3112234 INSPEC Abstract No: A88057235 Author(s): Allendoerfer, R.D.; Froncisz, W.; Felix, C.C.; Hyde, J.S. Corp Source: Dept. of Radiol., Med. Coll. of Wisconsin, Milwaukee, WI, USA Title: Electrochemical generation of free radicals in an EPR loop-gap resonator Source: Journal of Magnetic Resonance, vol.76, no.1 p. 100-5 ISSN: 0022-2364 CODEN: JOMRA4 Publication: USA Translated In: A10 Language: English Year: Jan. 1988 Copyright No: 0022-2364/88/$3.00 Treatment: P Practical Record Type: Journal Paper Abstract: An electrochemical cell for in situ generation of free radicals in a loop-gap resonator at X band is described. The cell is assembled from commercially available components and requires no glass blowing. The design is flexible and accommodates a variety of electrodes and electrode geometries. Remarkably small amounts of material are required. The filling factor is favorable for short-lived radicals. Performance of the cell is demonstrated by generation of the dianion radical of p-nitrobenzoic acid (13 Refs.) Descriptor(s): electrochemical electrodes; electrolysis; free radicals; negative ions; organic compounds; paramagnetic resonance of free radicals Identifier: electrochemical generation; anion; free radicals; EPR loop-gap resonator; X band; electrode geometries; filling factor; dianion radical; p-nitrobenzoic acid Class Code: A3330 (Electron paramagnetic resonance and relaxation); A8245 (Electrochemistry and electrophoresis) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 1017 Accession No: 3046057 INSPEC Abstract No: A88011110 Author(s): Hubbell, W.L.; Froncisz, W.; Hyde, J.S. Corp Source: Jules Stein Eye Inst., California Univ., Los Angeles, CA, USA Title: Continuous and stopped flow EPR spectrometer based on a loop gap resonator Source: Review of Scientific Instruments, vol.58, no.10 p. 1879-86 ISSN: 0034-6748 CODEN: RSINAK Publication: USA Translated In: A15 Language: English Year: Oct. 1987 Copyright No: 0034-6748/87/101879-08$01.30 Treatment: P Practical Record Type: Journal Paper Abstract: A continuous and stopped flow EPR spectrometer based on a new loop gap resonator operating at X band is described. The important features of the instrument are: (1) very small amounts of material are consumed in both stopped and continuous flow modes of operation, (2) dead times on the order of 4 ms for stopped flow and 1 ms for continuous flow are realized with a very narrow age distribution in the sample compartment, and (3) the dead times and, hence, sample age are highly reproducible and independent of viscosity due to the use of a positive displacement syringe ram. The performance of the instrument is evaluated using the decay of ascorbate radical generated by Ce(IV) oxidation and reduction of nitroxides by ascorbic acid (14 Refs.) Descriptor(s): magnetic resonance spectrometers; microwave spectrometers; paramagnetic resonance Identifier: stopper flow mode; organic compounds; stopped flow EPR spectrometer; loop gap resonator; X band; continuous flow modes; dead times; sample age; positive displacement syringe ram; decay of ascorbate radical; ascorbic acid; 4 ms; 1 ms; NO/sub x/; Ce Class Code: A0758 (Magnetic resonance spectrometers, auxiliary instruments and techniques) Chemical Indx: NO/bin N/bin O/bin; Ce/ss Numerical Ind: time 4.0 E-03 s; time 1.0 E-03 s -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: FirstSearch indicates your institution owns the item. Libraries that Own Item: 234 Accession No: 3011643 INSPEC Abstract No: A87139341 B87077638 Author(s): Hornak, J.P.; Szumowski, J.; Bryant, R.G. Corp Source: Depts. of Biophys., Radiol., & Chem., Rochester Univ. Med. Center, NY, USA Title: Elementary single turn solenoids used as the transmitter and receiver in magnetic resonance imaging Source: Magnetic Resonance Imaging, vol.5, no.3 p. 233-7 ISSN: 0730-725X CODEN: MRIMDQ Publication: UK Translated In: A04 Language: English Year: 1987 Copyright No: 0730-725X/87/$3.00+.00 Treatment: P Practical Record Type: Journal Paper Abstract: A single turn solenoid, also called a loop-gap resonator, is a device that is efficient for radio frequency spectroscopy on relatively large samples. Thus, the device provides an effective means for magnetic imaging where the single turn solenoid may serve both as the transmitter and receiver coil. The device is readily constructed and provides very efficient use of radio frequency (RF) power for imaging extremities such as breasts, arms, feet, and hands. The resulting magnetic images are acquired in short times with good anatomical resolution and considerable reduction of the RF power delivered to the patient (6 Refs.) Descriptor(s): biomedical equipment; biomedical NMR; solenoids Identifier: breast; arm; feet; hand; medical NMR imaging; elementary single turn solenoids; diagnostic imaging; transmitter; receiver; magnetic resonance imaging; loop-gap resonator; anatomical resolution; RF power Class Code: A8740 (Biomagnetism); A8760G (Laser beams, microwaves, and other electromagnetic waves); A8770E (Diagnostic methods and instrumentation); B5180F (Solenoids and electromagnets); B7510B (Radiation and radioactivity applications) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Provider: OCLC Database: INSPEC Ownership: Check the catalogs in your library. Libraries that Own Item: 138 Accession No: 2970595 INSPEC Abstract No: A87118858 Author(s): Drogendijk, A.C.; Barkhuijsen, H.; de Beer, R.; van Ormondt, D.; Postma, H.; den Hartog, H.W. Corp Source: Dept. of Appl. Phys., Delft Univ. of Technol., Netherlands Title: Electron spin echo envelope modulation (ESEEM) in CaF/sub 2/:Gd/sup 3+/K/sup +/ Source: Hyperfine Interact. (Switzerland), Hyperfine Interactions, vol.35, no.1-4 p. 1065-9 ISSN: 0304-3843 CODEN: HYINDN Publication: Switzerland Translated In: D17 Language: English Sponsor: IUPAP; Indian Nat. Sci. Acad.; Gov. India.; CSIR, India; et al Conference: Seventh International Conference on Hyperfine Interactions Conference Loc: Bangalore, India; 8-12 Sept. 1986 Year: 1987 Treatment: X Experimental Record Type: Conference Paper; Journal Paper Abstract: The energy levels of the nucleus of a K/sup +/ ion near a paramagnetic Gd/sup 3+/d ion, both substituted in CaF/sub 2/, have been measured with the recently developed technique of electron spin echo envelope modulation, combined with an also recently developed microwave cavity, the loop-gap resonator. The results provide confirmation of the theory of lattice distortion around substituted ions (7 Refs.) Descriptor(s): calcium compounds; gadolinium; paramagnetic resonance of rare earth ions and impurities; potassium; spin echo (EPR) Identifier: energy levels; electron spin echo envelope modulation; microwave cavity; loop-gap resonator; lattice distortion; CaF/sub 2/:Gd/sup 3+/K/sup +/ Class Code: A7630K (Rare-earth ions and impurities) Chemical Indx: CaF2:GdK/ss Ca/ss F2/ss Gd/ss F/ss K/ss CaF2/bin GdK/bin Ca/bin F2/bin Gd/bin F/bin K/bin GdK/dop Gd/dop K/dop --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------