Improvement of the dissociation energy of the hydrogen molecule (Part two)

Hoelsch, Nicolas

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https://hdl.handle.net/2142/100634 Copy

Description

Title

Improvement of the dissociation energy of the hydrogen molecule (Part two)

Author(s)

Hoelsch, Nicolas

Contributor(s)

• Jungen, Christian
• Ubachs, Wim
• Salumbides, Edcel John
• Eikema, K.S.E.
• Bethlem, Hendrick
• Niu, Ming Li
• Hussels, Joël
• Cheng, Cunfeng
• Merkt, Frederic
• Agner, Josef A.
• Beyer, Maximilian

Issue Date

2018-06-22

Keyword(s)

Comparing theory and experiment

Abstract

The dissociation energy D0 of ortho H2 is a benchmark quantity in quantum chemistry, with recent QED calculations now approaching accuracies achievable in simple atoms. In the light of recent discrepancies between experiment and theory [1], a combined effort (see also part one) has been undertaken to provide an improved experimental value for D0. We report the transition frequency from the GK 1Σ + g (v = 1, N = 1) state to the 56p (N = 1, S = 0, F = 0 − 2) Rydberg state belonging to the series converging on the X+ 2Σ + g (v + = 0, N + = 1) ground state of ortho H+ 2 . A resonant three-photon excitation scheme was employed, using pulsed VUV and VIS laser sources to reach the intermediate GK state and a continuous-wave near-infrared (NIR) laser source for the transition to the Rydberg state. To reach the desired accuracy, the procedure involved [2]: (i) minimizing the Doppler width through the use of a doubly skimmed, supersonic molecular beam produced by a cryogenic pulsed valve, (ii) minimizing stray electric and magnetic fields, (iii) cancelling the first-order Doppler shift using two counterpropagating laser beams, (iv) calibrating the NIR-laser frequency using a frequency comb referenced to an atomic clock. The ionization energy of the intermediate GK state was obtained by adding the binding energy of the Rydberg state determined previously by millimeter-wave spectroscopy and multichannel quantum-defect theory [3]. In combination with the GK 1Σ + g (v = 1, N = 1) ← X 1Σ + g (v = 0, N = 1) transition frequency presented in part one, an order-of magnitude improvement for D0 at the 10−9 level of accuracy has been achieved, while remaining consistent with the previously most precise determination [4]. [1] M. Puchalski et al., Phys. Rev. A 95, 052506 (2017) [2] M. Beyer et al., Phys. Rev. A 97, 012501 (2018) [3] D. Sprecher et al., J. Chem. Phys. 140, 104303:1-18 (2014) [4] J. Liu et al., J. Chem. Phys. 130 (17), 174306 (2009)

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Permalink

http://hdl.handle.net/2142/100634

DOI

10.15278/isms.2018.FC07

Copyright and License Information

Copyright 2018 Nicolas Hoelsch

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