Application of Vapor Pressure Isotope Effect to the Determinationof Vibrational Anharmonicity in the Liquid Phase

Abstract

The experimentally observed H/D vapor pressure isotope effects in chloroform and bromoform were combined with reliable spectroscopic data from the literature in order to obtain information on the change of the potential curve of the CH stretching motion on vapor-liquid transition. The parameters studied include the Morse potential parameters, the anharmonicity constant and the harmonic, cubic and quartic force constants in both phases. While the anharmonic character of the potential energy curve of the CH oscillator of chloroform has been found to decrease on condensation. the opposite behavior has been observed in the case of bromoform.