Powder Reflection Measurements of Some Divalent Lead Halides

Abstract

Abstract Powder reflection spectra are recorded of α‐ and β‐PbF 2 , PbCl 2 , PbBr 2 , PbFCl, and PbFBr. The measurements are compared with available absorption and specular reflectance spectra. The characteristic exciton of the lead halides manifests itself as a maximum in the powder reflection spectra owing to a prevailing specular component of reflectance. An additional low‐energy absorption appearing in the powder spectra of PbF 2 after a thermal treatment, is ascribed to incorporation of O 2− impurity. The low‐energy absorption visible in the powder reflection spectra of PbFCl and PbFBr is attributed to either (hydr.) oxide impurity or nonequimolar composition regarding F − and Cl − or Br − . α‐ and β‐PbF 2 are photochemically active like the other lead halides.