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, the thiol analogue of methanol. The obtained sensitivity coefficients in this molecule range from Kμ=−14.8 to +12.2 for transitions with a lower-level excitation energy below 10\,cm−1.
Cite
@article{arxiv.1304.5249,
title = {Methyl mercaptan (CH3SH) as a probe for $\mu$ variation},
author = {Paul Jansen and Li-Hong Xu and Isabelle Kleiner and Hendrick L. Bethlem and Wim Ubachs},
journal= {arXiv preprint arXiv:1304.5249},
year = {2013}
}