RAMAN AND INFRA-RED STUDIES OF DEFECTSTheory of F-centre Raman scattering in SrF2 R. H. Bartram, M. C. K. Wiltshire and W. Hayes J. Phys. Colloques, 41 C6 (1980) C6-465-C6-467 DOI: 10.1051/jphyscol:19806121