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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
Subject(s):Comparing theory and experiment
Abstract:The dissociation energy $D_0$ of ortho H$_2$ 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 $D_0$. We report the transition frequency from the $GK~^1\Sigma_g^+~(v=1, N=1)$ state to the 56p~$(N=1, S=0,F=0-2)$ Rydberg state belonging to the series converging on the $X^+~^2\Sigma_g^+~(v^+=0,N^+=1)$ 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 $GK~^1\Sigma_g^+~(v=1,N=1) \leftarrow X~^1\Sigma_g^+~(v=0,N=1)$ transition frequency presented in part one, an order-of magnitude improvement for $D_0$ at the $10^{-9}$ level of accuracy has been achieved, while remaining consistent with the previously most precise determination [4]. \footnotesize{[1] M. Puchalski et al., Phys. Rev. A 95, 052506 (2017)}\quad\quad\quad\quad\quad \footnotesize{[2] M. Beyer et al., Phys. Rev. A 97, 012501 (2018)} \footnotesize{[3] D. Sprecher et al., J. Chem. Phys. 140, 104303:1-18 (2014)}\quad\quad \footnotesize{[4] J. Liu et al., J. Chem. Phys. 130 (17), 174306 (2009)}
Issue Date:06/22/18
Publisher:International Symposium on Molecular Spectroscopy
Citation Info:APS
Genre:Conference Paper / Presentation
Type:Text
Language:English
URI:http://hdl.handle.net/2142/100634
DOI:10.15278/isms.2018.FC07
Other Identifier(s):FC07
Date Available in IDEALS:2018-08-17
2018-12-12


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