A pulse radiolysis study of poly(methyl methacrylate) in the presence of pyrene has been carried out in the temperature range 100-295 K. The concentration of pyrene was changed from 10(-3) to 10(-1) mol dm(-3). The absorption/emission spectra and kinetics of solute excited states and solute radical ions were investigated. It was found that pyrene excited states were formed as a result of their radical ion recombination in a time scale up to seconds. The decay of solute radical ions was influenced by photobleaching and can be described by a time-dependent rate constant. The activation energy of Py ions decay was temperature dependent and was equal to 35.7 and 1.2 kJ/mol for temperatures >T-gamma and

Keywords:CHARGE-TRANSFER;RADICAL-ION;POLYMETHYLMETHACRYLATE;PHOSPHORESCENCE;LUMINESCENCE;POLYETHYLENE;RADIATION;EMISSION;MATRICES;POLYMERS