Pulsed ESR and Molecular Motions
Phase relaxation measurments by electron spin echo (ESE) affords the estimation of the correlation time of the motion in the region up to 10-5 s. The results of theoretical and experimental analysis of the effect of methyl group rotation in nitroxide radicals have been proposed.
The method of pulsed saturation involving detection of ESE signal allows the range of the measured times to be extended up to the values of about 10-2s. The rotation of CH2 group in the CH2CO2- radical and thet of the CH3 group in the CH3CHCO2- radical have been investigated,
The method of pulsed saturation combined with pulsed scanning of Ho value allows the analysis of the rotation-induced redistribution of the pulsed saturation throughout the ESR spectra of the radicals. This version of pulsed ESR has been used to study the mobility of nitroxide spin labes and probes.