Radiolysis of alcohols at low temperatures. Part 3.—Spectrophotometric investigation of trapped electrons and other species formed by gamma-irradiation in glassy methanol

Abstract

The absorption spectrum of electrons trapped in a glassy methanol matrix was investigated and its parameters were determined. The changes of these parameters on optical bleaching and their kinetics were studied; it followed that the broad spectrum is an envelope of partial spectra corresponding to different kinds of trapped electrons and to their various quantum transitions. The parameters of the spectra are influenced by the presence of some solutes.

On optical bleaching, the electrons are excited to higher levels from which they collapse to a molecule giving the CH₃O^– ion and simultaneously a hydrogen atom. In accordance with this mechanism, the change in the yields of trapped electrons and total hydrogen caused by the presence of electron scavengers correspond to each other. The efficiencies of electron scavengers at 77K parallel roughly those in liquids at room temperature.

The absorption of the irradiated glassy methanol in the u.-v. is evidently due to CH₂OH radicals as deduced from the kinetics of their disappearance and their reaction with tetranitromethane.