Very low temperature pulse radiolysis. Protiated and perdeuterated methanol glasses at 6 K

Spectra resulting from the pulse radiolysis of glasses CH3OH and CD3OH at 6 K were observed. The absorption maxima of these spectra (625 nm for CH3OH and 720 nm for CD3OD-observed 100 ns after the beginning of the electron pulse) are only slightly red shifted from the absorption maximum obtained when either of these alcohols is γ irradiated at 4.2 K (i.e., 600 nm). Bleaching studies indicate that these γ radiolysis spectra are composed of a visible part which is due to solvated electrons and an infrared part which is due to trapped electrons. The infrared portions of the pulse radiolysis spectra at 6 K are enhanced compared to the above γ radiolysis spectra, and they decay to the latter spectra by a process which is approximately first order. Benzyl chloride also reduces the infrared absorptions which are produced by an electron pulse at 6 K more effectively than it reduces the visible absorptions. The species which is responsible for the transient infrared absorption at 6 K is tentatively identified as an electron localized in either a very shallow trap or a trap which is geminate to its parent cation. In either case, since these pulse radiolysis spectra are fully developed immediately after the electron pulse, it is concluded that electrons are localized in preexisting potential wells which may be either deep or shallow in vitreous methanol. 50 references, 5 figures, 3 tables