ESR investigations

Hdfer P, Grupp A, Nebenfuhr H and Mehring M 1986 Hyperfine sublevel correlation (HYSCORE) spectroscopy a 2D ESR investigation of the squaric acid radical Chem. Phys. Lett. 132 279-82... 

Diacyl-3,4-dihydroxythiophenes have been formulated as dienol tautomers (77T191). The same holds for 2,5-diaryl- and 5-aryl-2-carboxy derivatives (91JHC1449). ESR investigations of 6-halogeno-benzo[h] thiophene-2,3-semidiones (Scheme 13) have been reported (81JOC751). 

The dependence of the PL intensity and peak position on oxidation temperature for three different PS samples is shown in Fig. 7.20. Oxidation at 600°C destroys the PL, while the initial PL intensity is restored or even increased after oxidation at 900°C. This effect can be understood as a quenching of PL because of a high density of defects generated during the desorption of hydrogen from the internal surface of PS. Electron spin resonance (ESR) investigations show a defect with an isotropic resonance (g= 2.0055) in densities close to 101 cm for oxidation at 600°C [Pel, Me9]. This corresponds to one defect per crystallite, if the crystallite diameter is assumed to be about 5 nm in diameter. 

Cowsik, R. K., Srinivasan, R. ESR investigation of copper(II) bis-diethyldithiophos-phate in single crystals. Chem. Phys. Letters 16, 183 (1972). 

Bi—Mo—O and U—Sb—O in many aspects. The participation of oxygen from the V2Os lattice is proved by the selective oxidation capacity of the catalyst in the absence of gas phase oxygen, while ESR investigations have shown the reduction of Vs + to V4+ and demonstrated a correlation between the activity and the V4+ content of a working catalyst. These facts strongly support the assumption of a redox mechanism. 

Antimonates were also the subject of ESR investigations, and it was shown by Suzdalev et al. [310] that in Sn—Sb—O combinations only reduction of Sbs+ takes place. The initial value of the Sb5+/Sb3+ ratio is 1 for Sb204) 2.3 for Sn—Sb—O and 4.3 for Fe—Sb—O. These last two values are strongly reduced by chemisorption of acrolein. The Sb3+ spectrum shows a change after formation of a complex with the adsorbate. 

This different behavior can be explained by the conformation of the radicals and by stereoelectronic effects [6]. Electron spin resonance (ESR) investigations have revealed that the D-glucopyranosyl radical 7 does not adopt the 4C1 conformation 7a, but is distorted into the B2 5 shape 7b (Scheme 5) [7,8], The equatorial-like attack at the boat conformer... 

Earlier, an ESR investigation of complexes formed between Zn, Cd and Hg and several paramagnetic imidazolin-l-oxyl free radicals had been reported.437 For a given ligand, the changes in the 14N hyperfine splittings can be correlated with the formation constants, and the following order of stability is observed Hg>Cd>Zn. 

Esr investigations were done of catalysts samples with reactants adsorbed at room and at reaction temperature. Also the preparations of deactivated and regenerated catalyst were studied. From all studied nitro compounds only the following nitrobenzene (parameters of esr signal g = 2.0031 , a H v = 7 Gs inten-... 

New evidence for the importance of one electron donor centres for catalytic transfer reduction has arisen from esr investigations. Both, heating of anion... 

Donor-acceptor complexes are formed (by ji-ji interaction) between arylhydrazones and trinitrofluorenes190, chloranil and tetracyanoethylene191. ESR investigation of donor-acceptor mixtures in DMSO and in acetonitrile reveals the presence of a small degree of charge transfer. 

Two types of initiator were used in this work, AIBN and uranyl nitrate. Unreacted initiator was thoroughly removed from the polymer. A comparison of PVC samples prepared by the two different initiators showed identical behavior under ESR investigation. Therefore, end groups derived from the initiator do not appear to affect the course of degradation appreciably. 

Howe and Grdtzel deduced from esr investigations that the hole is trapped in a subsurface oxygen anion (reaction (7.7)) [11a]. 

A considerable number of ESR investigations have been devoted to the study of halogen-containing organic radicals. Their objectives were numerous knowledge of the structure... 

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