13C and 33,34S isotope effects on the vapor pressure of liquid carbon disulfide

Abstract

Prompted by the experimental investigation of Betts and Buchannon a thorough analysis of CS2 vapor pressure isotope effects has been made in the context of the theory of isotope effects in condensed phases and the available spectroscopic information. The agreement between the calculated and experimental results is satisfactory. The calculated results may be empirically described by the equations[Formula: see text]and[Formula: see text]The analysis indicates that the principal contribution to the 13C isotope effect is due to the shift on condensation of the asymmetric stretching frequency Δν3, and quantitatively corroborates the theoretical conclusion reached earlier by Akopyan, Girin, and Bakshiev and others of the magnitude of the dielectric correction for this band. The 34S effects are principally determined by the hindered rotation and translation in the liquid and the shift in the symmetric stretching motion Δν1