Excess electrons in aqueous glasses and crystalline ice

Abstract

Experimental studies of excess electrons in aqueous glasses and crystalline ice are reviewed. Emphasis is placed on studies of the two main optical absorption bands, the well known visible band, which is similar to that of the solvated electron in water, and the IR band which has λmax [Formula: see text] 2950 nm. Under some circumstances partial conversion of the IR-absorbing species to the visible-absorbing species has been observed. Evidence indicates that the two species are due to electrons trapped in distinctly different physical environments. Two mechanisms have been proposed for the formation of the visible-absorbing electron in crystalline ice, one involving naturally occurring vacancies and the other radiation produced vacancies. Studies of the UV and visible luminescence emitted when ice at low temperature is irradiated are summarized, and the mechanisms suggested for its production are discussed briefly. The studies on excess electrons in aqueous solids seem to the authors to be highly relevant to the more recent studies of electron solvation in water which are done on a much shorter time-scale. These latter studies are reviewed briefly with the aim of elucidating the relevance.Key words: visible-absorbing electrons, IR-absorbing electrons, irradiation of aqueous glasses, irradiation of crystalline ice, electron solvation in water.