Raman scattering from molten Li and Rb halides

Polarised and depolarised light scattering spectra are reported for molten LiCl, LiBr, LiI, RbCl, RbBr and RbI. All measurements have been made at about 30 degrees C above melting point and over spectral ranges covering almost the entire width of the spectra (700 cm-1 for Li salts, and 300 cm-1 for Rb salts), with the only portion left undetected being the range below the low-frequency shift limit nu of 4 cm-1. both polarised and depolarised spectra of Rb salts lack any distinct structure whereas pronounced shoulders occur in both the polarised and the depolarised spectra of the molten Li salts. The depolarisation ratios rho d decrease in all cases with increasing v from relatively high values in the low-frequency shifts to more or less constant values in the higher-frequency region; the overall depolarisation ratio of Rb salts decreases with increasing anion size but, significantly for Li salts, rho d increases with increasing anion size. An overall comparison is made of spectral profiles, depolarisation ratios, intensities and high-frequency decay constants of 15 molten salts including those reported in previous papers.