title: Characterising molecules for fundamental physics: an accurate spectroscopic model of methyltrioxorhenium derived from new infrared and millimetre-wave measurements.
abstract: Precise spectroscopic analysis of polyatomic molecules enables many striking advances in physical chemistry and fundamental physics. We use several new high-resolution spectroscopic devices to improve our understanding of the rotational and rovibrational structure of methyltrioxorhenium (MTO), the achiral parent of a family of large oxorhenium compounds that are ideal candidate species for a planned measurement of parity violation in chiral molecules. Using millimetre-wave and infrared spectroscopy in a pulsed supersonic jet, a cryogenic buffer gas cell, and room temperature absorption cells, we probe the ground state and the Re[double bond, length as m-dash]O antisymmetric and symmetric stretching excited states of both CH3187ReO3and CH3185ReO3isotopologues in the gas phase with unprecedented precision. By extending the rotational spectra to the 150-300 GHz range, we characterize the ground state rotational and hyperfine structure up to J = 43 and K = 41, resulting in refinements to the rotational, quartic and hyperfine parameters, and the determination of sextic parameters and a centrifugal distortion correction to the quadrupolar hyperfine constant. We obtain rovibrational data for temperatures between 6 and 300 K in the 970-1015 cm-1range, at resolutions down to 8 MHz and accuracies of 30 MHz. We use these data to determine more precise excited-state rotational, Coriolis and quartic parameters, as well as the ground-state centrifugal distortion parameter DKof the187Re isotopologue. We also account for hyperfine structure in the rovibrational transitions and hence determine the upper state rhenium atom quadrupole coupling constant eQq'.
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, UMR 8233, MONARIS, F-75005, Paris, France and CNRS, UMR 8233, MONARIS, F-75005, Paris, France. pierre.asselin@upmc.fr.
authors.forename: Pierre
authors.initials: P
authors.lastname: Asselin
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, UMR 8233, MONARIS, F-75005, Paris, France and CNRS, UMR 8233, MONARIS, F-75005, Paris, France. pierre.asselin@upmc.fr.
authors.forename: Yann
authors.initials: Y
authors.lastname: Berger
authors.affiliation: Univ. Lille, CNRS, UMR 8523 - PhLAM - Physique des Lasers Atomes et Molécules, F-59000 Lille, France.
authors.forename: Thérèse R
authors.initials: TR
authors.lastname: Huet
authors.affiliation: Univ. Lille, CNRS, UMR 8523 - PhLAM - Physique des Lasers Atomes et Molécules, F-59000 Lille, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Margulès
authors.affiliation: Univ. Lille, CNRS, UMR 8523 - PhLAM - Physique des Lasers Atomes et Molécules, F-59000 Lille, France.
authors.forename: Roman
authors.initials: R
authors.lastname: Motiyenko
authors.affiliation: Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, UK.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Hendricks
authors.affiliation: Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, UK.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Tarbutt
authors.affiliation: Université Paris 13, Sorbonne Paris Cité, Laboratoire de Physique des Lasers, F-93430 Villetaneuse, France and CNRS, UMR 7538, LPL, F-93430 Villetaneuse, France. benoit.darquie@univ-paris13.fr.
authors.forename: Sean K
authors.initials: SK
authors.lastname: Tokunaga
authors.affiliation: CNRS, UMR 7538, LPL, F-93430 Villetaneuse, France. benoit.darquie@univ-paris13.fr and Université Paris 13, Sorbonne Paris Cité, Laboratoire de Physique des Lasers, F-93430 Villetaneuse, France.
authors.forename: Benoît
authors.initials: B
authors.lastname: Darquié