Radiation damages of organic materials at 4 K: an ESR study of polyethylene and related hydrocarbons

To characterize the radiation damages produced at 4 K in polyethylene and related hydrocarbons, a series of studies have been carried out by using electron spin resonance spectroscopy. It has been found that the local concentration of radiation induced paramagnetic species is considerably higher in the irradiation at 4 K than that at 77 K. The causes of this irradiation temperature effect on the spatial distribution of radicals have been extensively studied. It is suggested that the suppression of hydrogen atom migration and the reactivity of hydrogen atoms at 4 K play an important role in the low temperature radiation damages of saturated hydrocarbons. In the present paper the results previously and newly obtained are surveyed and discussed as a whole. (author)