OPTICAL-ABSORPTION SPECTRA OF LOCALIZED-ELECTRONS GENERATED AT 1.6-K IN POLAR MATRICES - EVIDENCE FOR PRESOLVATED ELECTRONS

Glassy samples of ethanol, methanol + 5 mol % water, 10 M and 18 M NaOH in H2O, 5 M K2CO3 and 7 M NaClO4 in D2O were x irradiated at 1.6 K. After irradiation the optical absorption spectra of the localized electrons generated were recorded at 1.6 K. Red shifts relative to spectra after irradiation at 4.2 K were observed in all matrices indicating stabilization of some presolvated electrons characterized by a nonequilibrium first solvation shell. Particularly in deuterated matrices, where observation further into the infrared is possible, a long infrared tail assigned to presolvated electrons is detected at 1.6 K; these infrared tails are not stabilized at 4.2 K. Analysis of the spectral shifts after irradiation at 77, 4.2, and 1.6 K indicates that an increasingly larger population of presolvated electrons is stabilized as the temperature is lowered and that a parallelism for electron solvation exists in all the matrices studied including ethanol. In the methanol and aqueous matrices, electron solvation is much more efficient than in ethanol, and the predominant population of localized electrons is largely solvated even at 1.6 K. The spectral shifts in 18 M NaOH glasses are also consistently interpreted in terms of presolvated electron stabilization and do not require postulation of (Na+-e-) pair stabilization as suggested in earlier work at 77 K. © 1979 American Institute of Physics.