Thursday, September 24, 2020, 16:00
OSGA/EG06
Frederic Merkt, ETHZ
Abstract:
Few-electron molecules are attractive systems for precision spectroscopy
because their properties can be calculated with high accuracy by
quantum-chemical methods [1,2,3]. The measurements serve to test
theoretical predictions, ideally at the level where their accuracy is
limited by the uncertainties of the fundamental constants or by
unrecognized physical effects. I will report on precision measurements
of energy intervals in cold samples of H_2. In particular, we determine
the ionization energy with a precision (Delta nu/nu) of 10^(-10) from
high-resolution Rydberg spectra [4,5] and derive the dissociation energy
with an accuracy of 350 kHz, approaching the level where the uncertainty
in the proton-to-electron mass ratio would limit the accuracy of
otherwise exact calculations. Comparison will be made to recent
theoretical results in the context of a more-than-100-year-long series
of experimental and theoretical determinations of the dissociation
energy of H_2. I will also discuss the determination of an upper bound
for a hypothetical global shift of the energy level structure of
ortho-H_2 with respect to that of para-H_2. If time permits, the results
of similar experiments in He_2 will also be presented [6].
[1] V. I. Korobov, L. Hilico and J.-P. Karr, Phys. Rev. Lett. 118,
233001 (2017).
[2] M. Puchalski, J. Komasa, P. Czachorowski, and K. Pachucki, Phys.
Rev. Lett. 122, 103003 (2019).
[3] E. Matyus, J. Chem. Phys. 149, 194112 (2018).
[4] M. Beyer, N. Hölsch, J. A. Agner, J. Deiglmayr, H. Schmutz and F.
Merkt, Phys. Rev. A 97, 012501 (2018).
[5] N. Hölsch, M. Beyer, E. J. Salumbides, K. S. E. Eikema, W. Ubachs,
Ch. Jungen, and F. Merkt, Phys. Rev. Lett. 122, 103002 (2019).
[6] M. Beyer, N. Hölsch, J. Hussels, C.-F. Cheng, E. J. Salumbides, K.
S. E. Eikema, W. Ubachs , Ch. Jungen, and F. Merkt, Phys. Rev. Lett. 123,
163002 (2019).
[7] L. Semeria, P. Jansen, G.-M. Camenisch, F. Mellini, H. Schmutz, and
F. Merkt, Phys. Rev. Lett. 124, 213001 (2020)