Optical and ESR Studies on Triphenylimidazolyl Radicals Produced by Photolysis and Radiolysis at Low Temperature

Abstract

The characteristic temperature-dependent behavior exhibited by the solution of the photochromic dimer of triphenylimidazolyl (photo-dimer) has been reinvestigated by means of optical and ESR spectroscopy. Assuming two conformations for triphenylimidazolyl radical, the spectral change at low temperatures has been elucidated in terms of a conformational isomerization of the radical and dimerization of the radical to a colorless dimer. Photo-dimer in γ-irradiated glassy solutions undergoes a dissociative electron attachment to produce triphenylimidazolyl radical and its anion.