Adenine complexes of thymine and uracil: electron spin resonance and thermoluminescence investigations

Abstract

Electron spin resonance (E.S.R.) and thermoluminescence (T1) studies following irradiation with high-energy electrons and ⁶⁰Co λ-rays have been carried out at room temperature and at low (77°Κ) temperature. Adenine, thymine and uracil and their two equimolecular complexes, adenine-thymine and adenine-uracil, have been used in these investigations. E.S.R. measurements at room temperature showed that the complexes were more resistant to radiation, and the differences in the free-radical yields of the complexes on the one hand, and their constituents on the other, follow dose-response patterns that are specific to the complexes. Low-temperature E.S.R. measurements carried out before and after T1 have indicated that the E.S.R. signal originates in at least two groups of electrons, probably only one of which is active for T1. These studies also show that the modes of transfer of radiation damage in the two complexes are different. These results are further substantiated by quantitative measurements on the photo-bleaching characteristics of thermoluminescence of the samples.