The effect of melting on the multiphonon infrared absorption spectra of KBr, NaCl and LiF

Measurements have been made at temperatures between 300 K and 1160 K of the multiphonon infrared absorption by samples of crystalline and molten KBr, NaCl and LiF 1-2 mm thick. The relatively small change in the spectra which accompanies the melting transition is pertinent to the organisation of molten salt dilution studies and implies that at least the high frequency limits of the respective vibrational spectra are approximately the same in the solid and liquid phases close to the melting point.