Anharmonicity in the Symmetric and Asymmetric CH Vibrations of Ethylene

Abstract

The vibrational anharmonicity in the CH stretching vibrations of ethylene has been calculated from a simple anharmonic potential function. xs, the difference between the harmonic frequency ωs and the observed frequency νs, in those vibrations which are asymmetric in a CH2 group appears to be systematically about 35 cm−1 greater than in the symmetric vibrations. A similar, though smaller (∼20 cm−1) effect appears in the deformation vibrations.