Electrons trapped in ethanol-water glasses at ultra-low temperatures

Abstract

The trapping of electrons in ethanol-water glasses has been studied by pulse radiolysis at temperatures from 6 to 76 K and by γ-radiolysis from 4.2 to 80 K. Addition of water, or increase in temperature, causes the visible absorption band of the spectrum of trapped electrons to increase relative to the IR band. Closer examination of these bands showed that they behave independently in the temperature range 4.2–50 K. It is concluded that both temperature and water content influence the distribution of electrons between pre-existing traps. The distribution of trap depths is non-random and comprises two sets, i.e. shallow (hydrocarbon) and deep (hydroxyl). Gϵ values measured in γ-radiolysis experiments at 4.2 K are much lower than those measured by pulse radiolysis at 6 K. This difference is probably caused by slow charge recombination by tunnelling which involves e - t mainly from the shallow traps.