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. x_s, the difference between the harmonic frequency ω_s and the observed frequency ν_s, 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.