OPTICAL AND ELECTRICAL PROPERTIES OF THIN FILMS OF ALPHA-LEAD AZIDE

The optical absorption spectrum of α-lead azide was measured in the region 185-700 mμ at room, liquid nitrogen and liquid helium temperatures. Absorption coefficients were determined from the diffuse reflectance of powders and from transmission measurements on thin films. The spectral response of photoconductivity of thin films was determined from room temperature down to 77°K. The thin films of lead azide were prepared by vacuum depositing a thin film of metallic lead on either quartz or sapphire substrates followed by exposure of the lead film to gaseous hydrazoic acid. The results indicate that the fundamental absorption is at shorter wavelengths than indicated previously. Structure not previously reported has been found in the optical absorption and photoconductivity data and has been interpreted in terms of fundamental exciton structure. © 1969.