Molecular Composition of Alkali Halide Vapors

Abstract

An analysis of the velocity distribution of the molecules which escape through an ideal aperture from an isothermal enclosure has been made for ten alkali halides (CsCl, CsBr, RbCl, KCl, KI, NaF, NaCl, NaI, LiCl, and LiBr). It is found that there is a significant abundance of dimers in all cases except those of the cesium salts, and that an observable concentration of trimers occurs for NaF, LiCl and LiBr. Observation of the relative abundances of the polymers as the temperature of the effusing gas and the pressure within the source is varied permits the determination of the energy of dissociation of the dimer into two monomers and of the trimer into a monomer and dimer.