One useful technique for studying radiation- formed cations is the measurement of luminescence caused by charge recombination. This has been shown by several studies, which have indicated that luminescence is induced when irradiated hydrocarbon glasses containing solutes such as aromatic compounds are warmed (thermolumines- cence) or stimulated by visible or infrared light (photoluminescence). The luminescence has been identified as fluorescence and/or phosphorescence of solute molecules induced by charge recombina- tion between electrons and solute cations"z'"'18'. Similar studies have also been extended to neat