ESR spectra of the carboxylated cyclohexadienyl radicals: 13C hyperfine constants and the effect of carboxylation on the g factors and proton hyperfine constants

1975 ◽  
Vol 62 (8) ◽  
pp. 3093-3108 ◽  
Author(s):  
Klaus Eiben ◽  
Robert H. Schuler
Keyword(s):  
Esr Spectra ◽  
Hyperfine Constants ◽  
G Factors

TEMPERATURE DEPENDENCES OF Y2Cu2O5 ESR SPECTRA

1989 ◽  
Vol 03 (05) ◽  
pp. 427-435 ◽  
Author(s):  
A.A. GIPPIUS ◽  
V.V. MOSHCHALKOV ◽  
YU. A. KOKSHAROV ◽  
A.N. TIKHONOV ◽  
B.V. MILL ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Single Crystal ◽  
Room Temperature ◽  
Esr Spectra ◽  
Single Line ◽  
Néel Temperature ◽  
Esr Spectrum ◽  
Complicated Form ◽  
Temperature Dependences ◽  
G Factors

Temperature dependences of the ESR spectrum in Y 2 Cu 2 O 5 compound are studied for both polycrystalline and single crystal samples. The g-factors along the main axes are found to be ga=2.099, gb=2.048, and gc=2.21 at room temperature, T=293 K . As temperature decreases, the linewidth ΔH increases in agreement with the Huber’s formula ΔH=A(T N /(T−T N ))β+B(θ/T+1) with the following parameters: A=1513±10 Oe , B=509±10 Oe , T N =7±1 K , θ=18±2 K , β=1.3±0.3. In the vicinity of the Neel Temperature, T N , the ESR spectrum has a very complicated form indicating the existence of clusters with different internal magnetic fields. Below T N , a single line symmetrical ESR spectrum is recovered.

Radiative lifetimes and hyperfine constants for the 3d complex of molecular hydrogen

1978 ◽  
Vol 56 (7) ◽  
pp. 827-837 ◽  
Author(s):  
C. W. T. Chien ◽  
F. W. Dalby ◽  
J. Van Der Linde
Keyword(s):  
Hyperfine Structure ◽  
Cross Sections ◽  
Molecular Hydrogen ◽  
Molecular Properties ◽  
Radiative Lifetimes ◽  
Hyperfine Constants ◽  
Complete Basis ◽  
Hanle Effect ◽  
Doubly Excited ◽  
G Factors

Accurate experimental radiative lifetimes, disalignment cross sections, hyperfine constants, and Zeeman g factors are reported for a number of rotational levels of the 3d electronic complex and the nearby doubly excited K1Σg+ state of molecular hydrogen. The 3d complex of states is not a complete basis for calculation of the above molecular properties. A theory of the Hanle effect in the presence of hyperfine structure is presented.

ESR of •NH2 and •N2H4+ Free Radicals Produced by Gamma Irradiation in NH3OHCl, (NH3OH)2SO4 and N2H6SO4

1985 ◽  
Vol 40 (9) ◽  
pp. 903-905 ◽  
Author(s):  
F. Köksal ◽  
O. Çakir ◽  
İ. Gümrükçü ◽  
M. Birey
Keyword(s):  
Free Radicals ◽  
Gamma Irradiation ◽  
Single Crystals ◽  
Room Temperature ◽  
Esr Spectra ◽  
Hyperfine Constants

Abstract Free radicals produced by gamma irradiation in single crystals of hydroxylammonium chloride, hydroxylammonium sulfate and hydrazinium sulfate have been investigated at room temperature with ESR. The radicals in the hydroxylammonium salts were identified as •NH2 and that in hydrazinium sulfate as •N2H4+ . The ESR spectra of the radicals were unchanged and undiminished at room temperature more than eight months after irradiation. The g and hyperfine constants were found to be almost isotropic with an average g = 2.0047, aH = 2.0 mT and αN = 0.70 mT for •NH2 and g = 2.0034, aH = 1.10 mT and aN = 1.15 mT for •N2N4+ .

Carbon-13 hyperfine constants, g-factors and electronic structure of m-benzosemiquinone radical anions

1982 ◽  
Vol 86 (15) ◽  
pp. 2926-2929 ◽  
Author(s):  
Keith P. Madden ◽  
Hugh J. McManus ◽  
Robert H. Schuler
Keyword(s):  
Electronic Structure ◽  
Radical Anions ◽  
Hyperfine Constants ◽  
G Factors

Kinetics of the Thermal Disappearance of Radicals Formed During the Radiolysis of Aspartic Acid

2009 ◽  
Vol 59 (12) ◽  
Author(s):  
Mihai Contineanu ◽  
iulia Contineanu ◽  
Ana Neacsu ◽  
Stefan Perisanu
Keyword(s):  
Thermal Resistance ◽  
Aspartic Acid ◽  
Room Temperature ◽  
Esr Spectra ◽  
Complex Mechanism ◽  
Radical Species ◽  
Mechanisms Of Formation ◽  
Kinetics Of

The radiolysis of the isomers L-, D- and DL- of the aspartic acid, in solid polycrystalline state, was investigated at room temperature. The analysis of their ESR spectra indicated the formation of at least two radicalic entities. The radical, identified as R3, resulting from the deamination of the acid, exhibits the highest concentration and thermal resistance. Possible mechanisms of formation of three radical species are suggested, based also on literature data. The kinetics of the disappearance of radical R3 indicated a complex mechanism. Three possible variants were suggested for this mechanism.

Photolytic and thermal annealing of radical anions gamma-irradiated monocarboxylic acids

1979 ◽  
Vol 44 (12) ◽  
pp. 3632-3643 ◽  
Author(s):  
Karel Mach ◽  
Igor Janovský ◽  
Karel Vacek
Keyword(s):  
Thermal Annealing ◽  
Pivalic Acid ◽  
Esr Spectra ◽  
Paramagnetic Species ◽  
Radical Anions ◽  
Γ Irradiation ◽  
Before And After ◽  
Optical Bleaching ◽  
The Difference ◽  
Gamma Irradiated

Total yields of paramagnetic species, their optical bleaching and thermal annealing in acetic, propionic, a-butyric, isobutyric, and pivalic acid γ-irradiated at 77 K were followed by ESR spectroscopy. Radical anions, always found after irradiation, disappear during optical bleaching without formation of any paramagnetic product. During thermal annealing they are converted almost quantitatively into the α-radicals of the respective acid, with the exception of pivalic acid. Amounts of radical anions were estimated from the difference of integrated ESR spectra taken before and after optical bleaching. The results show that approximately equal amounts of the reduction and oxidation paramagnetic products of the γ-irradiation can be detected.

Electrochemical behaviour and ESR spectra of nitro substituted mono- and dibenzoylmethylenebenzthiazolines and selenazolines

1979 ◽  
Vol 44 (5) ◽  
pp. 1540-1551 ◽  
Author(s):  
Jaro Komenda ◽  
Jiří Huzlík
Keyword(s):  
Electron Transfer ◽  
Esr Spectroscopy ◽  
Electrochemical Behaviour ◽  
Spectroscopic Studies ◽  
Esr Spectra ◽  
Slow Electron

Compounds of the type of 2-(4'-nitrobenzoyl)methylene-3-ethylbenzothiazoline (I) and 2-bis-(p-nitrobenzoyl)methylene-3-ethylbenzothiazoline (II) were studied polarographically and by ESR spectroscopy to obtain informations about their electrochemical and follow-up reactions and their conformation. Whereas with compounds of the type I the conjugation in their molecules is preserved, with type II the coplanarity of the molecules is disturbed, which is manifested in the values of the splitting constants of the ESR spectra and a slow electron transfer between both nitrophenyl substituents. These conclusions are supported by NMR spectroscopic studies.

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