Abstract

A linear relationship has been found between the wavenumber of the CH₃ symmetrical deformation vibration and the electron density on the CH₃ carbon as calculated from CNDO/2 molecular orbital theory. Other CH deformation vibrations are also related to the electron density on the carbon and, as a result, can be correlated with the CH₃ symmetrical deformation wavenumber. These include ν‾(CH₂ def), ν‾(CH₂ wag) and both components of ν‾(CH wag). The splitting of ν‾(CH₃ sym def) in isopropyl and <i>t</i>-butyl groups has long been known. It is shown here that the effect is due to an interaction force constant relating to the CH₃ symmetrical deformation vibrations of two or three different neighboring CH₃ groups. The origin of the interaction is thought to be an H,H' repulsion between hydrogens on the different CH₃ groups.

Infrared radio-frequency double-resonance spectra of CH₃OH in the CH₃ deformation state and torsionally excited states

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Complete frequency coverage for submillimeter laser spectroscopy with optically pumped CH₃OH, CH₃OD, CD₃OD, and CH₂CF₂

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