Raman intensities are calculated for the torsional vibrations of methylcyclopropane and propylene oxide using an anisotropic atomhyphen;point dipole interaction model to calculate the elements of the molecular polarizability tensor. It is predicted that electrical anharmonicity contributes substantially to the intensities of both the Dgr;v= 1 and dgr;v= 2 transitions. The calculated intensity distribution of the Dgr;v= 1 transitions of propylene oxide is in excellent agreement with experiment. The calculated intensities of the fundamental transitions of methylcyclopropane are not in as good agreement with experiment as those of propylene oxide; however, the observed transitions of the former molecule are extremely broad and difficult to measure accurately. The calculations predict that the Dgr;v= 1 transitions of both molecules are substantially more intense than the Dgr;v= 2 overtones. The intensity of the overtones cannot be measured accurately because they are partially obscured by intense inhyphen;dand outhyphen;ofhyphen;plane bending vibrations of the methyl groups. (AIP)
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