ESR studies of some γ‐irradiated organic crystals

Abstract

AbstractAcrylamide, N‐tert‐butylacrylamide, and propionamide crystals were irradiated at −196°C and the structures of radicals studied by ESR spectroscopy at various temperatures. The γ‐irradiated acrylamide crystals show a five‐line spectrum which is similar in shape to the signal obtained from the γ‐irradiated propionamide crystals. Two types of radicals are produced in irradiated acrylamide and propionamide crystals at −196°C. When the irradiated samples are kept at −78°C the spectrum of propionamide remains the same, except in intensity. In contrast to this, the acrylamide spectrum changes to a triplet because of dimerization. Upon warming the irradiated acrylamide sample to between −50 and −30°C, some small new peaks become apparent on either side of the triplet. These new peaks disappear above −20°C and the spectrum changes to a triplet because of polymerization. To observe the changes in the ESR spectra of γ‐irradiated N‐tert‐butylacrylamide we kept the sample at various temperatures from −196 to 100°C. From −196°C to about room temperature the spectrum is a quintet. At and above 35°C, the spectrum changes to a triplet with shoulders on either side of the main peaks. With further warming above 80°C the spectrum changes to a broad triplet.