Raman Spectrum of the Liquid PbCl2–KCl System

The Raman spectra of PbCl2, 2PbCl2·KCl, PbCl2·KCl, and PbCl2·2KCl were recorded both in the molten state and in the solid state. The spectrum of solid PbCl2 exhibits three Raman lines which are explainable on the basis of linear structure for PbCl2 molecules in the lattice. The spectra of 2PbCl2·KCl and PbCl2·KCl are interpreted on the basis of a predominance of PbCl3— ions with pyramidal structure C3v. For PbCl2·2KCl, a distorted tetrahedral structure for the PbCl42— ion (C2v) is found. Force constants for the ionic species are calculated using valence force potentials.