Growth and spectroscopic characterization of Pb2+:CaF2 crystals

CaF2 crystals doped with various concentrations of PbF2 (0.4, 0.5, 1 and 2 mol%) were grown in vacuum, in a shaped graphite furnace using the vertical Bridgman method. The optical absorption spectra reveal the four characteristic UV absorption bands (labeled A, B, C and D) of the Pb2+ ions. As the PbF2 concentration increases, the structure of the bands become clearly visible, that is characteristic for the ns(2) ions in various hosts. High intensity emission bands in the near UV spectral region have been observed. The dependence on the Pb2+ concentration of the optical absorption and emission of the Pb2+: CaF2 crystals were not reported before.