The radiolysis of alcohols at low temperature—I. The precursors of hydrogen in glassy methanol

Abstract

Using various electron and hydrogen atom scavengers the γ-irradiation yields of different hydrogen precursors in glassy photobleached methanol were determined: the yields of the trapped electrons, of the independently formed hydrogen atoms, of the hot hydrogen atoms and of the ‘molecularly’ formed hydrogen are 2·3, about 0·5, about 1·1 and about 0·3 respectively. Some conclusions about the separation of electrons from their conjugated ions are drawn from the comparison of these yields with those for liquid methanol. In acid methanol glass G(H 2) is larger by 0·5 than in neutral glass. A possible explanation is offered, namely, that a low excited state of methanol is decomposed by the influence of the electric field of the ions. When the irradiated methanol glass is warmed in the dark—thermally bleached—the yields of hydrogen and glycol are smaller but the reasons for this are not quite clear. Also the crystalline methanol gives questionable results. A few remarks on the process of electron trapping are added.