Prospects for high-resolution microwave spectroscopy of methanol in a Stark-deflected molecular beam

Abstract

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 Starkdeflected molecular beam. We have calculated the Stark shift of the lower rotational levels in the ground torsion-vibrational state of CH 3 OH and CD 3 OH 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 CH 3 OH at an accuracy below 10 −8 .

Molecular Asymmetry and Optical Cycling: Laser Cooling Asymmetric Top Molecules

“…These motions are present in any molecule containing an internal rotor with local C 3v symmetry, but have no analog in linear or symmetric top molecules. For instance, torsion-rotation transitions in both methanol (HOCH 3 ) and methyl mercaptan (HSCH 3 ) have been found to offer significant enhancement factors [122][123][124]. Table III includes the lasercoolable analogs of these molecules, e.g.…”

A cryofuge for cold-collision experiments with slow polar molecules

“…S2). The comparably lower flux results from both the weaker Stark shifts (27 ) and the much lower vapor pressure of methanol. We have achieved a similar flux of ~1 × 10 8 s -1 for isopropanol, but maintaining stable operation requires additional effort because isopropanol is prone to freezing owing to its even lower vapor pressure.…”

Search for the variation of fundamental constants: Strong enhancements inXΠ2cations of dihalogens and hydrogen halides

“…Several polyatomic molecules were suggested for laboratory studies of VFC as well, see e.g. [33,34] and references in [9,11]. Here we note that practical advantage can be gained by using molecular ions rather than neutral molecules due to the greater ease of trapping and cooling [35,36].…”