Knowledge Bank

Torsional combination bands of $CH3SCl$ and $CH3CHO$ have been studied, in which the molecule was simultaneously excited by one or two vibrational quanta plus the torsion. The results will be compared with a model assuming the methyl torsion to be an anharmonic vibration and with the model of a sinusoidal potential opposing the internal $CH3$ rotation. For $CH3SCl$ the torsional fundamental will also be discussed, and the derived potential barrier will be compared with the one obtained from microwave spectroscopy.