Bulletin of the American Physical Society
52nd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Monday–Friday, May 31–June 4 2021; Virtual; Time Zone: Central Daylight Time, USA
Session E02: Focus Session: Molecular Spectroscopy for Fundamental Physics
2:00 PM–3:48 PM,
Tuesday, June 1, 2021
Chair: Thad Walker, Wisconsin
Abstract: E02.00001 : Fundamental physics with molecular hydrogen ions*
2:00 PM–2:30 PM
We have performed precise rotational and vibrational spectroscopy of trapped HD+, sympathetically cooled by laser-cooled beryllium ions.
Our measurements allow (i) a test of the correctness of the high-precision theory results, (ii) a determination of certain fundamental constants, and (iii) testing for hypothetical deviations of the proton-deuteron interaction from the Coulomb force.
Obtaining precise experimental transition frequencies require a Doppler-free spectroscopy technique. We achieved this with ensembles of molecules rather than with single molecules by loading a moderate number into the linear r.f. trap, where the ions arrange in a string-like fashion on the trap axis. Irradiation of the spectroscopy laser is performed orthogonally to the trap axis. Under these conditions we observed one-photon electric-dipole transitions with resolved carrier, both with THz radiation and with mid-infrared radiation. Line resolution as high as 3×1011 and transition frequency uncertainties as low as 3×10-12 were achieved.
Measured rotational and vibrational frequencies are in agreement with predictions. Assuming the correctness of the predictions, we determined values of the ratio of reduced nuclear mass and electron mass as well as of the electron-proton mass ratio. Their uncertainties are competitive with the best direct determinations using Penning trap mass spectroscopy. The upper limit for deviations from the nuclear Coulomb force was lowered by more than one order. Opportunities for further progress will be presented.
*ERC 786306, DFG Schi 431/23-1, INST-208/737-1, FP7-2013-ITN 'COMIQ', Prof. Behmenburg-Schenkung
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