Raman spectra of undoped and uranium doped CaF_2 single crystals

摘要

Raman scattering experiments for nominally pure and uranium doped CaF_2 single crystals were presented. In all crystals, the Raman active T_(2g) vibration mode of CaF_2 was observed, whose frequency shift and full-width at half-maximum (FWHM) broadening correspond well with defects and impurities in CaF_2 lattice. Additional Raman peaks develop in nominally pure CaF_2 with high etch pits density and U~(6+):CaF_2 crystals. Part of additional Raman peaks in the experimental results, which are assumed due to vibration modes from F~- interstitials and vacancies, are in well agreement with the theoretical predications by employing the Green-function formulation.