Speaker
Description
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$^{4,5,6}$ and derive the dissociation energy with an accuracy of 350 kHz, approaching the level where the size of the proton and 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$_2$.
- V. I. Korobov, L. Hilico and J.-P. Karr, Phys. Rev. Lett. 118, 233001 (2017).
- M. Puchalski, J. Komasa, P. Czachorowski, and K. Pachucki, Phys. Rev. Lett. 122, 103003 (2019).
- E. Mátyus, J. Chem. Phys. 149, 194112 (2018).
- M. Beyer, N. Hölsch, J. A. Agner, J. Deiglmayr, H. Schmutz and F. Merkt, Phys. Rev. A 97, 012501 (2018).
- C.-F. Cheng et al., Phys. Rev. Lett. 121, 013001 (2018).
- N. Hölsch et al., Phys. Rev. Lett. 122, 103002 (2019).
