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

Films 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.