Pulse radiolysis studies on liquid alkanes and related polymers

Absorption spectra of alkane radical cations, alkane excited states, and alkyl radicals and electrons in irradiated neat liquid alkanes at room temperature were assigned on subnanosecond and nanosecond time scale after an electron pulse. Two broad visible and near-infrared absorption bands of alkane excited states and radical cations, and UV absorption band of alkyl radicals were observed in neat n-alkanes. In neat cyclohexane and trans-decalin, very broad visible absorption band mainly due to alkane excited states and UV absorption band of alkyl radicals were observed. In neat neopentane and isooctane, visible absorption bands were not observed, although UV absorption bands of alkyl radicals were observed. The wavelengths of absorptive peaks of alkane radical cations and excited states become longer with increasing the number of carbon atoms of n-alkanes. The lifetimes of alkane radical cations become shorter with decreasing number of carbon atoms of n-alkanes and are shorter than those of electrons in neat alkanes. In irradiated ethylene-propylene copolymers, broad absorption bands of excited states and tail parts of absorption bands of radical cations and electrons were observed in visible and near-infrared region.