Recently, the extremely sensitive torsion-rotation transitions in methanol have been used to set a tight constraint on a possible variation of the proton-to-electron mass ratio over cosmological time scales. In order to improve this constraint, laboratory data of increased accuracy will be required. Here, we explore the possibility for performing high-resolution spectroscopy on methanol in a Stark-deflected molecular beam. We have calculated the Stark shift of the lower rotational levels in the ground torsion-vibrational state of CH3OH and CD3OH molecules, and have used this to simulate trajectories through a typical molecular beam resonance setup. Furthermore, we have determined the efficiency of non-resonant multi-photon ionization of methanol molecules using a femtosecond laser pulse. The described setup is in principle suited to measure microwave transitions in CH3OH at an accuracy below 10^{-8}.
@article{arxiv.1302.7245,
title = {Prospects for high-resolution microwave spectroscopy of methanol in a Stark-deflected molecular beam},
author = {Paul Jansen and Isabelle Kleiner and Congsen Meng and Ronald M. Lees and Maurice H. M. Janssen and Wim Ubachs and Hendrick L. Bethlem},
journal= {arXiv preprint arXiv:1302.7245},
year = {2015}
}