Luminescence and structural properties of modified AgBr films

The phenomena of free charge carrier excitation, trapping and recombination are the basic electronic processes responsible for latent image Formation. Photoluminescence measurements are widely used to obtain informations about these processes. Furthermore, evaporated silver halide layers are suitable model systems for investigations of the photographic process. Therefore, evaporated films of AgBr and mixed layers of AgBr and PbC2(2) were prepared and their temperature dependent luminescence behaviour was investigated. The pure AgBr films consist of microcrystallites with a size of about 90 nm. The size of the AgBr microcrystallites in the mixed layer is in the range from 15 nm to 50 nm and depends on the concentration of the admixture. The mixed layers show an increased intrinsic and an extended spectral photographic sensitivity with a maximum at an admixture concentration of 23 vol-% PbC2(2). In the luminescence spectra (10 K) of the pure AgBr films, two emission bands at 495 nm and 588 nm were detected. The ratio of the intensities of both lines changes with increasing temperature and is influenced by the admixture due to the suppression of the emission band at 588 nm by charge transfer processes.