The effect of condensation on vibrational anharmonicity as determined by the vapor pressure isotope effect

Abstract

Consideration of the continuing successes of the theory of condensed phase isotope effects in the harmonic approximation leads to the conclusion that relative changes expected in anharmonic constants on condensation are constrained to be of the same order of magnitude or smaller than the corresponding changes in harmonic force constants. Benzene-deuterobenzene isotope efforts are analyzed in an illustrative example and a brief discussion of other cases, including CS 2 and CHCl 3, is given.