STETTER, M and MAULWURF, M and MULLER, A (1991) DYNAMICS OF METHYL-GROUPS IN PYRIMIDINE 5-YL RADICALS STUDIED BY ENDOR SPECTROSCOPY. MOLECULAR PHYSICS, 72 (3). pp. 607-618. ISSN 0026-8976,
Full text not available from this repository.Abstract
The total torsional potential height V and the average jump time (T --> infinity) tau-infinity for the hindered methyl rotation in the 5-yl radicals of 5-methylbarbituric acid (. MBS) and thymidine (. TH) are determined by studying the temperature dependence of ENDOR intensities. Single crystals, powder and glass samples are examined. The results obtained from the glass samples differ significantly from those obtained from single crystals of the same substance. It is found that V = 2.0 +/- 0.4 kJ mol-1, tau-infinity = 0.4 +/- 0.1 ps for . MBS single crystals, V = 5.5 +/- 0.6 kJ mol-1, tau-infinity = 0.11 +/- 0.02 ps for . TH single crystals and V = 1.8 +/- 0.4 kJ mol-1, tau-infinity = 0.8 +/- 0.2 ps for . TH glass. To obtain the dynamical parameters for the methyl group motion in low hindering potentials, a theoretical description of the temperature dependence of ENDOR intensities is developed that is based on a general diffusion model for the methyl group rotation. It is shown that the theoretical result for the enhancement is nearly independent of the shape of the hindering potential.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | ; |
| Depositing User: | Dr. Gernot Deinzer |
| Last Modified: | 19 Oct 2022 08:46 |
| URI: | https://pred.uni-regensburg.de/id/eprint/55079 |
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