Vibrational Spectra of Inorganic Molecules. II. Infrared Reflection Spectra of Liquid Lithium, Sodium, Potassium, and Silver Nitrates

The optical constants of liquid lithium, sodium, potassium, and silver nitrates have been obtained by a one‐angle‐reflection method using the analysis of Robinson and Price. The derived absorption spectra are consistent with the Raman spectra observed by Bues and suggest that in all melts, the point group symmetry of the cations about the nitrate ion does not contain D3h as a subgroup. Further, in both lithium and silver nitrate the highest symmetry subgroup common to the nitrate ion and the surrounding cations is at most C2v and in these melts the nitrate ion is not rotating freely about its threefold axis. In all the melts there is a low‐frequency band which must be ascribed to a cation‐anion vibration of a lattice‐like type. The intensity of the a2″ band has been discussed and the bond dipole moment derived has been interpreted in terms of the polarizing field of the cations.