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.

FREE RADICALS OF BIOLOGICAL INTEREST: PART II. ELECTRON SPIN RESONANCE (ESR) SPECTRA OF 2537 A IRRADIATED AMINO ACIDS

1967 ◽  
Vol 45 (12) ◽  
pp. 1831-1839 ◽  
Author(s):  
W. F. Forbes ◽  
P. D. Sullivan
Keyword(s):  
Amino Acids ◽  
Electron Spin Resonance ◽  
Electron Spin ◽  
Hydrogen Abstraction ◽  
Esr Spectra ◽  
Side Chain ◽  
Biological Interest ◽  
Spin Resonance ◽  
Cyclohexadienyl Radical ◽  
Secondary Radical

Polycrystalline amino acids, when irradiated with 2537 Å light, afford a variety of electron spin resonance signals. These signals are generally stable at room temperature for relatively long periods of time. For a number of the spectra obtained, there is evidence that more than one radical species contributes to the observed spectra. The signals obtained frequently differ from those obtained on exposure to ionizing radiation. The postulated species formed can often be visualized as being formed by effective hydrogen abstraction from the alkyl-substituted tertiary carbon atom or from the —OH, —SH or —NH group contained in the side chain. For L-phenylalanine a secondary radical is obtained, which is ascribed to a cyclohexadienyl radical.

Electron spin resonance observations of photochemically generated contact ammonium ion-pairs of fluoro-substituted ketones

1979 ◽  
Vol 57 (5) ◽  
pp. 600-602 ◽  
Author(s):  
K. S. Chen ◽  
T. Foster ◽  
J. K. S. Wan
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Ion Pairs ◽  
Esr Spectra ◽  
Ammonium Ion ◽  
Spin Resonance ◽  
Photochemical Systems

Contact radical ion-pairs of ammonium and fluoro-substituted ketones were generated in photochemical systems and their here-to-fore elusive esr spectra were characterized.

Electron Spin Resonance Investigations on Perovskite Solar Cell Materials Deposited on Glass Substrate

MRS Advances ◽  
2018 ◽  
Vol 3 (32) ◽  
pp. 1831-1836
Author(s):  
C. L. Saiz ◽  
E. Castro ◽  
L. M. Martinez ◽  
S. R. J. Hennadige ◽  
L. Echegoyen ◽  
...  
Keyword(s):  
Electron Spin Resonance ◽  
Solar Cell ◽  
Line Width ◽  
Electron Spin ◽  
Glass Substrate ◽  
Esr Spectra ◽  
Perovskite Solar Cell ◽  
Hole Transport ◽  
Ex Situ ◽  
Spin Resonance

ABSRTACTIn this article, we report low-temperature electron spin resonance (ESR) investigations carried out on solution processed three-layer inverted solar cell structures: PC61BM/CH3NH3PbI3/PEDOT:PSS/Glass, where PC61BM and PEDOT:PSS act as electron and hole transport layers, respectively. ESR measurements were conducted on ex-situ light (1 Sun) illuminated samples. We find two distinct ESR spectra. First ESR spectra resembles a typical powder pattern, associated with gx = gy = 4.2; gz = 9.2, found to be originated from Fe3+ extrinsic impurity located in the glass substrate. Second ESR spectra contains a broad (peak-to-peak line width ∼ 10 G) and intense ESR signal appearing at g = 2.008; and a weak, partly overlapped, but much narrower (peak-to-peak line width ∼ 4 G) ESR signal at g = 2.0022. Both sets of ESR spectra degrade in intensity upon light illumination. The latter two signals were found to stem from light-induced silicon dangling bonds and oxygen vacancies, respectively. Our controlled measurements confirm that these centers were generated during UV-ozone treatment of the glass substrate –a necessary step to be performed before PEDOT:PSS is spin coated. This work forms a significant step in understanding the light-induced- as well as extrinsic defects in perovskite solar cell materials.

The Influence of the Type of Dipping Composition on the Structure of Aramid Cord Threads

2018 ◽  
Vol 45 (4) ◽  
pp. 171-173
Author(s):  
L.N. Andreikova ◽  
S.P. Bobrov ◽  
Yu.O. Andriasyan ◽  
S.G. Karpova ◽  
I.A. Mikhailov
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Correlation Time ◽  
Physicomechanical Properties ◽  
Electron Spin Resonance Spectroscopy ◽  
Resonance Spectroscopy ◽  
Service Properties ◽  
Radical Concentration ◽  
Spin Resonance ◽  
Different Types

Publications concerned with the influence of the type of dipping composition on the adhesion, physicomechanical, and service properties of aramid cord threads of grades Arom-75 (Rusar-75), Arom-175 (Rusar-175), and Rusar-200 are analysed. According to current ideas, the type of dipping composition affects not only the adhesion and physicomechanical properties of aramid cord but also its structure. Using electron spin resonance spectroscopy, we studied specimens of dipped Arom-75 cord threads and undipped threads (for comparison). The parameters characterising the structural state of the investigated polymer specimens were determined: the correlation time, the radical concentration in the investigated specimen, and the ratio of the proportion of dense amorphous regions to the proportion of loose amorphous regions. Data for cord based on Ruslan® threads dipped in two different compositions and data for undipped cord were compared. The possibility of changing the structure of cord and the service properties of mechanical rubber goods with an aramid skeleton by using different types of dipping composition was shown.

Microscopic Study of Metal Hydrides using Electron Spin resonance

1980 ◽  
Vol 3 ◽  
Author(s):  
E. L. Venturini
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Metal Hydrides ◽  
Esr Spectra ◽  
Spectroscopic Technique ◽  
Host Lattice ◽  
Hydrogen Ions ◽  
Spin Resonance ◽  
Symmetry Phase ◽  
Paramagnetic Ions

ABSTRACTElectron spin resonance (ESR) of dilute paramagnetic ions in nonmagnetic metallic hydrides provides microscopic information about the hydrogen ions in the immediate vicinity of the impurity. By comparing ESR spectra for different host metals and several hydrogen/metal ratios, one can determine material properties including host lattice symmetry, phase boundaries and occupation of available sites by hydrogen. Examples are presented of ESR of dilute Er in group IIIB and IVB metal hydrides, demonstrating the sensitivity and versatility of ESR as a spectroscopic technique.

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.

An ESR and calorimetric study of iron oolitic samples from the Northampton ironstone

Clay Minerals ◽  
1990 ◽  
Vol 25 (3) ◽  
pp. 303-311 ◽  
Author(s):  
A. U. Gehring ◽  
R. Karthein
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Hyperfine Splitting ◽  
Esr Spectroscopy ◽  
Thermal Conversion ◽  
Esr Spectra ◽  
Calorimetric Study ◽  
Calorimetric Methods ◽  
Mineral Phases ◽  
Spin Resonance

AbstractElectron spin resonance (ESR) spectroscopy and calorimetric methods were used to characterize conversion processes in multimineral samples from the Northampton ironstone (NIS) at temperatures between 25°C and 800°C. The beginning of the thermal conversion processes can be determined by the formation of asymmetric ESR spectra with g ≈ 2 at 250°C. The breakdown of the berthierine structure between 250°C and 520°C is indicated by the disappearance of the hyperfine splitting in the Mn2+ spectrum and the formation of magnetite. The decomposition of siderite and calcite was found by calorimetric methods at 580°C and 700°C, respectively. The hematite formation between 550°C and 800°C is explained by the decomposition of siderite but also by the oxidation of previously formed magnetite. The occurrence of hematite as the dominant ferric oxide at 800°C signifies the end of the conversion process of the major mineral phases in the NIS samples.

Dielektrische Relaxation und Elektronenspinrelaxation von Eisen(III)acetylacetonat in verdünnter Lösung/ Dielectric Relaxation and Electron Spin Relaxation of Ferric Acetylacetonate in Dilute Solutions

1976 ◽  
Vol 31 (5) ◽  
pp. 457-462
Author(s):  
W. Dietz ◽  
H. Kilp ◽  
W. Noerpel ◽  
M. Straßmann ◽  
M. Stockhausen
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Correlation Time ◽  
Wave Length ◽  
Dilute Solutions ◽  
Electron Spin Relaxation ◽  
Electron Spin Resonance Linewidth ◽  
Spin Resonance ◽  
Solvent Molecules ◽  
Permittivity Measurements

Abstract The dielectric loss and electron spin resonance linewidth of ferric acetylacetonate have been measured in dilute solutions of benzene, m-and p-xylene, mesitylene and carbon tetrachloride. Permittivity measurements were made at 10 frequencies in the microwave region (1.2 m to 1 mm wave-length), ESR measurement at 2 frequencies (X and Q band). The permittivity results show a broad non-Debye pattern, yielding a mean correlation time of about 4 ps. The ESR results yield a mean correlation time of about 3 ps. The parallelism between the results obtained by both methods is discussed in view of a common relaxation process, which is the transient deformation of the chelate system resulting from stochastic induction by neighbouring solvent molecules.

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