| Abstract: | The formation of radical ions in γ-irradiated polymethyl-methacrylate (PMMA) matrices at 77°K and thermal-induced reaction of these radical ions were of studied by optical absorption spectroscopic measurements. The radical ions of stilbene and pyrene were investigated. These radical ions decay according to second-order kinetics, which means that the neutralization reaction of the cationic species and anionic species participates in the decay process. The kinetic plots consist of two straight lines; that is, fast and slow decay processes are concerned. The activation energies were estimated to be Efast = 2.4 kcal/mol and Eslow = 6.4 kcal/mol, respectively. The probability of recombination reaction depends on the distance between cationic and anionic species. |
