The vibrationally averaged, temperature-dependent structure of polyatomic molecules. II. SO2

The thermally averaged molecular structure parameters of gaseous SO₂ have been measured by electron diffraction. Due to the anharmonicity of the molecular potentials and the resulting coordinate interactions in the potential the experimental parameters are temperature dependent. The data reveal this function. A comparison of our results with the theoretical ones of Kohl and Hilderbrandt show good agreement for the change of the structure values with temperature. As in the previous studies the measured mean square amplitudes of all atom pairs are consistently about 0.002 Å larger than the theories predict.