UV/VIS‐Spectroscopic Studies of Cold Condensed Metal/Metal Halide Films With and Without Matrix‐Isolation

Abstract

AbstractFilms of about 200 nm thickness were prepared by vacuum deposition of the halides onto fused silica windows, which were kept at 12 K by a closed cycle helium refrigerator. AgCl, CuCl, and TlCl films showed an structureless absorption edge which extended from about 350 nm to 200 nm. Annealing of the films below 170 K (150 K in the case of CuCl) for more than two hours gave no changes in the absorption spectra. Films which were annealed above this temperature showed at 12 K the exciton bands which are characteristic for the crystalline state of the materials. — Cocondensation of 1 to 30 mol% of metal Me to the halide MeCl gave rise to a broad absorption band around 300 nm which can be assigned to a surface plasmon excitation of small particles. When the films are annealed, these bands disappear simultaneously with the crystallization of the matrix, and a broad band between 400 and 500 nm is formed. We assume that this band is due to Mie scattering of metallic colloid particles. — The non‐crystalline state apparently is a metastable ionic glass phase. ‐Silver chloride, matrix isolated in Ar or Kr matrices on LiF windows shows an UV/VIS spectrum which is different from the gas spectrum. No new bands appear when it is cocondensed with silver atoms.