Evidence for a second kind of trapped electron in some deuterated aqueous glasses at low temperatures. A pulse radiolysis study

Several deuterated aqueous glasses were pulse-irradiated at 76 K. In addition to the known visible absorption band of the trapped electron, a second intense infrared absorption band has been found in 50 vol.% ethylene glycol, 9.5 M LiCl, and 2.5 and 4 M MgCl2. From the shape of band, the wavelength of max. absorption is estimated to be about 3600 nm and the extinction coefficient to be about 4.9 x 104 M-1 cm-1. Electron scavengers decrease the intensity of both bands, but to different extents. An increase in temperature decreases the intensity of the infrared band, but not that of the visible band. These and other features indicate that the infrared band is due to shallowly trapped electrons, which are distinctly different from trapped electrons that absorb in the visible region. In the two chloride glasses the decay of the infrared band is accompanied by emission, which is probably due to a spur reaction between an electron and a hydroxyl radical to form an excited hydroxide ion. No emission is found in the ethylene glycol glass, but growth of the visible band matches the decay of the infrared band in this case. (N.D.H.)