Hydrated Electrons Formed in the Flash Photolysis of Ag° and Tl°

Abstract

The transient species Ag0, formed in the reduction of Ag+ by hydrated electrons, may be photodissociated to eaq− again by light in the absorption band of Ag0 centered at ~315 nm.[Formula: see text]It suggests that this band is a charge-transfer-to-solvent band. The photon energy threshold for photoionization of Ag0 (3.0 eV) is substantially smaller than the vacuum photoelectric work function of silver metal (4.5 eV). Analogous results were obtained in solutions of Tl+ indicating that Tl0 may also yield eaq− on photolysis at ~300 nm. The experiments utilized a double flash photolysis technique, in which hydrated electrons were produced by u.v. photolysis of SO42− in the first flash, reacted with Ag+ or Tl+ to give the short-lived intermediates Ag0 (lifetime ~60 μs) and T10 (lifetime < 20 μs) which were photolyzed by a second flash containing light in a restricted wavelength range.