Electron spin resonance spectra of nitric oxide adsorbed on zeolites

1970 ◽  
Vol 48 (8) ◽  
pp. 1317-1322 ◽  
Author(s):  
C. L. Gardner ◽  
M. A. Weinberger
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Iterative Procedure ◽  
Axial Component ◽  
Axially Symmetric ◽  
Electric Field Gradients ◽  
Line Shapes ◽  
Field Gradients ◽  
Spin Resonance ◽  
Surface Fields

Electron spin resonance (e.s.r.) spectra of NO adsorbed on the 4 zeolites Linde 4A, 5A, 13X, and hydrogen mordenite were measured at 77°K. No e.s.r. signal was observed for NO on silica gel. By use of expressions for the line shapes of polycrystalline samples, assuming axially symmetric g-tensors, and taking into account also isotropic coupling, values of [Formula: see text] and line width were derived by an iterative procedure. From these, the crystal field splitting, Δ, of the 2pπ levels, which become non-degenerate on adsorption, were calculated. By relating Δ to the interaction of the non-axial components of the quadru-pole moment with the corresponding electric field gradients, the non-axial component of the latter is estimated for the surface fields of the zeolites.

THE ELECTRON SPIN RESONANCE OF Fe+3 IN SINGLE CRYSTALS OF SPODUMENE

1965 ◽  
Vol 43 (12) ◽  
pp. 2262-2275 ◽  
Author(s):  
A. Manoogian ◽  
F. Holuj ◽  
J. W. Carswell
Keyword(s):  
Electron Spin Resonance ◽  
Single Crystals ◽  
Electron Spin ◽  
Ground State ◽  
Electric Quadrupole ◽  
Spin Hamiltonian ◽  
Electric Field Gradients ◽  
Field Gradients ◽  
Spin Resonance ◽  
Quadrupole Resonance

The electron spin resonance (ESR) spectrum of Fe+3 in spodumene, LiAl(SiO3)2, has been investigated at 24 kMc/sec. One set of five "allowed" transitions between the magnetic sublevels of the 6S5/2 ground state has been detected. The following values have been assigned to the parameters occurring in the spin Hamiltonian (eq. (1)) (bnm in gauss): gx = 2.0086 ± 50, gy = 2.0100 ± 50, gx ± 2.0046 ± 25, b20 = −1 430, b22 = −282, b40 = −20, b42 = 108, b44 = −182. Consideration of electric field gradients measured by methods of electric quadrupole resonance and of the orthorhombic parameters b20 and b22 did not lead to a unique assignment of the Fe+3 impurity to one of the two available cationic sites in spodumene.

A Study of Cation-exchange Reactions in the System Potassium Durosemiquinone – Potassium Tetraphenylboride – Tetrahydrofuran

1971 ◽  
Vol 49 (9) ◽  
pp. 1529-1538 ◽  
Author(s):  
T. E. Gough ◽  
P. R. Hindle
Keyword(s):  
Electron Spin Resonance ◽  
Spectral Line ◽  
Cation Exchange ◽  
Line Width ◽  
Electron Spin ◽  
Potassium Ion ◽  
Exchange Reactions ◽  
Line Shapes ◽  
Intramolecular Exchange ◽  
Spin Resonance

The electron spin resonance (e.s.r.) spectrum of potassium durosemiquinone in tetrahydrofuran has been studied as a function of temperature and found to exhibit line-width alternation indicating the presence of an intramolecular migration of the potassium ion between the oxygens of the semiquinone. The addition of potassium tetraphenylboride to the system produces intermolecular scrambling of potassium, the spectral effects of which are superimposed upon those of the intramolecular exchange. From the spectral line-shapes approximate values of the activation energies and frequency factors were derived. The tetraphenylboride anion did not play a detectable role in the various exchange mechanisms.

Electron Spin Resonance of Hydrogenated Amorphous Silicon Alloyed with Sulfur

1997 ◽  
Vol 467 ◽  
Author(s):  
Baojie Yan ◽  
P. C. Taylor
Keyword(s):  
Electron Spin Resonance ◽  
Amorphous Silicon ◽  
Spin Density ◽  
Electron Spin ◽  
Hydrogenated Amorphous Silicon ◽  
Line Shapes ◽  
Single Defect ◽  
Spin Resonance ◽  
High Sulfur Concentration ◽  
Hydrogenated Amorphous

ABSTRACTElectron spin resonance (ESR) and light-induced electron spin resonance (LESR) measurements were performed on sulfur-doped hydrogenated amorphous silicon (a-SiS:H). At low S doping levels (H2S/SiH4 ≤ 10−3 in gas phase), the ESR and LESR line shapes are similar to those observed in undoped a-Si:H. The dark spin density generally increases with S doping and reaches 5×1016 cm−3 at H2S/SiH4 ≈ 10−3. On the other hand, at high S concentration, the dark spin density increases significantly with S concentration. The ESR and LESR line shapes become identical and asymmetric, a fact that implies the ESR and LESR signals result from the same kind of ESR center. Since S doping is very inefficient, the ESR signals probably are due to defects instead of trapped carriers in band tails. The asymmetry of the ESR and LESR line shapes at high sulfur concentration may result from either more than one type of defect or an asymmetry in the g tensor of a single defect. The photo-excitation of H-passivated, S-related defects could also contribute to the LESR.

An electron spin resonance spectral study of the dynamics of spin-labelled fatty acids bound to oxidoreductases

1983 ◽  
Vol 61 (2-3) ◽  
pp. 144-149
Author(s):  
Jenifer Thewalt ◽  
Tenkasi S. Viswanathan ◽  
Robert J. Cushley
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Correlation Time ◽  
Axial Ratio ◽  
Esr Spectra ◽  
Bacterial Luciferase ◽  
Theoretical Computer ◽  
Line Shapes ◽  
Spin Resonance ◽  
Axis Rotation

Electron spin resonance (ESR) spectra have been recorded for 5-doxylstearate (I) and 16-doxylstearate (II) in the presence of bacterial luciferase and soybean lipoxygenase. The acids are inhibitors of the enzymes (Kd ≈ 2 × 10−5 M for II bound to luciferase). Using theoretical computer simulations of the ESR line shapes, an effective correlation time of τeff ≈ 3.7 × 10−9 ± 0.5 × 10−9 s is found for the motion of spin label I bound to luciferase. Concentration-dependent sedimentation velocity experiments indicate luciferase is anisotropic and, assuming a prolate ellipsoid of axial ratio ≤ 9, a correlation time of τa ≈ 7.7 × 10−9 s is predicted for rotation about the luciferase long axis. The tightly bound spin-labelled inhibitors, therefore, are proposed to give rise to ESR spectra chiefly reflecting luciferase long axis rotation. The ESR spectra of I and II, bound to lipoxygenase and to luciferase, appear similar.

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