Knowledge Bank

Molecular beams of thioformaldehyde, $H2CS$, have been generated by pyrolysis of dimethyl disulfide in a quartz beam source. A large number of transitions in both ortho and para states have been observed, Hyperfine structure has been resolved for the $M=\pm 1$ to $M=0$ transition for the $110,211$, and $312$ rotational levels. These data yield the dipole moment, spin-spin interaction and spin-rotation interactions. In principle, these three transitions allow the determination of the three spin-rotation tensor elements. However, the very near symmetric top nature of thioformaldehyde makes this information very strongly correlated. This problem will be discussed for electric resonance measurements for other $C2V$ molecules such as ketene.