Vibrational spectra of anhydrous lithium perchlorate in crystalline and molten states

Abstract

Anhydrous lithium perchlorate has been examined in the crystalline and molten state by infrared and Raman spectroscopy. In the crystalline phase all degenerate modes are split but the Raman and infrared spectra are essentially identical in the internal frequency region. In the molten state the spectra are more simple but no coincidences exist between infrared and Raman spectra. The spectra are interpreted in terms of a crystalline symmetry perturbation for both the solid and molten salts. The symmetry of the perturbing field is shown to change in going from the solid to the melt. An explanation of the melt spectra in terms of contact ion pairs is considered and dismissed. Observed vibrational frequencies and assignments are given.