Knowledge Bank

The detection of spontaneous Raman scattering induced by an intense Ar ion laser in an intracavity cell containing $C2H6$ (either bulk or jet) has allowed the measurement of weak bands involving the excitation of the torsional mode $v4$. Barrier indcued splittings have been measured up to the fifth torsional level. Current theories for vibrational-torsional-rotational interaction in the case of a high barrier have been applied to interpret the Raman spectra. The calculated $\nu 4$ energy levels used in the simulation give a qualitative picture of the spectra. Quantitative agreement has been found up to the third overtone by choosing $V3=1009.1cm-1$ and $V6=11.0cm-1$. Measurement of $2\nu 9+2\nu 4,2\nu 6+2\nu 4$ and $2\nu 2+2\nu 4$ combination bands has given information on the effect of the molecular vibrations on the torsional barrier. New results on $CH3CD3$ will be presented as well.