Hydrogen-induced sensitization, photochromism, and giant IR absorption in thin silver iodide films

Abstract

New effects related to the behavior of atomic hydrogen in thin silver iodide (AgI) films have been observed. Hydrogen-induced sensitization produced simultaneously with illumination of the AgI film surface leads to a deep photolysis of the halide compound, which leads to the formation of silver clusters and colloids and produces a sharp change in the optical properties of the material (photochromism). The average diameter of the photolytic colloidal particles formed in AgI films does not exceed 20 nm, which accounts for their large specific surface. The adsorption of hydrogen-donor molecules used for the photosensitization on silver colloids gives rise to the giant IR absorption, which is related to the oscillations of atoms in adsorbed molecules. This phenomenon offers a probe for the investigation of atomic hydrogen photodetachment involved in AgI photosensitization.