Near-edge absorption of lead molybdate crystals

At 400 nm an absorption band is observed on annealed PbMoO4 which is shown to be simultaneously the excitation band for fluorescence emission and photoconductivity. It is strongly dichroitic and exhibits a very strong characteristic temperature dependence. By referring to the analytically known temperature dependence of the absorption edge of PbMoO4 crystals the observed temperature behaviour of absorption can be described and the energy of the phonons participating in the absorption process can be determined in good agreement with values published in literature for CaMoO4. All previous investigations suggest that an interaction of electron excitations (excitons) and phonons is responsible for the near-edge absorption of PbMoO4 crystals.