Methyl mercaptan (CH3SH) as a probe for variation of the proton-to-electron mass ratio

Torsion-rotation transitions in molecules exhibiting hindered internal rotation possess enhanced sensitivities to a variation of the proton-to-electron mass ratio. This enhancement occurs due to a cancellation of energies associated with the torsional and rotational degrees of freedom of the molecule. This effect occurs generally in every internal rotor molecule, but is exceptionally large in methanol. In this paper, we calculate the sensitivity coefficients of methyl mercaptan, which is the thiol analog of methanol. The obtained sensitivity coefficients in this molecule range from K