ENDOR characterization of the free radical in irradiated thymidine

The stable free radical produced by ionizing radiation in the nucleoside thymidine has been studied by ENDOR spectroscopy. The radical is formed by addition of hydrogen to the C6 carbon atom of the thymine ring. The hyperfine couplings of the CH2 protons and the methyl group rotational splitting constant are deduced from ENDOR measurements at 4.2°K.