Extreme Vacuum Ultraviolet Absorption Spectra of Silver Chloride and Silver Bromide Films

The absorption spectra of silver chloride and silver bromide films have been extended to shorter wavelengths than in previous studies, in order to locate the maxima and any associated structure and to find the magnitude of the absorption coefficient. Measurements in the region 800-1600 A were made by using a grazing-incidence vacuum spectrograph with a Lyman discharge tube as source. Overlapping of orders was avoided by using the noble gases as filters. Sample films of the order of 100 A thick were vacuum evaporated onto very thin (100-150 A) celluloid supports. The silver halide film thicknesses were measured by channeled spectra. Silver chloride shows its greatest absorption in the region 900-1200 A, with some structure. Silver bromide has a broad absorption maximum about 1500 A, with some structure at shorter wavelengths. With the films used, both compounds showed absorption coefficients at maxima of approximately 1.5 ×${10}^6$ ${\mathrm{cm}}^{-1\mathrm{}}$.