Optical absorption and photoconductivity spectra of localized electrons in x-irradiated aqueous 10M lithium chloride glasses at 4.2 K: Support for two types of localized electrons each with overlapping bound–bound and bound–continuum transitions

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Abstract
Irradiation of the 10M LiCl/H2O and 10M LiCl/D2O matrices at 4.2 K has shown that the localized electron species, e−vis (λmax∼680 nm) and e−ir (λmax≳2400 nm) observed previously by pulse radiolysis at 77 K, can be stabilized. Photobleaching and addition of nitrate as an electron scavenger show that e−ir does not appear to interconvert to e−vis. Thus e−ir does not appear to behave as a presolvated electron which is convertible into a solvated electron (i.e., e−vis) as observed in alcohols and other organic glasses. The wavelength dependence of the photoconductivity generated in these irradiated glasses was also measured. The photocurrent peaks at higher energy than the respective optical spectra for both e−vis and e−ir, hence both bound–bound and bound–continuum transitions are suggested for both species. The trap depth of e−vis appears to be two or more times deeper than that of e−ir, and the photoconductivity quantum efficiency of both species is 0.1−1 at 4.2 K at their respective photoconductivity maxima, ∼400 and 1400 nm.