Benchmarking Theory with an Improved Measurement of the Ionization and Dissociation Energies of H2

Nicolas Hölsch, Maximilian Beyer, Edcel J. Salumbides, Kjeld S. E. Eikema, Wim Ubachs, Christian Jungen, Frédéric Merkt
2019 Physical Review Letters  
The dissociation energy of H_2 represents a benchmark quantity to test the accuracy of first-principles calculations. We present a new measurement of the energy interval between the EF ^1Σ_g^+(v=0,N=1) state and the 54p1_1 Rydberg state of H_2. When combined with previously determined intervals, this new measurement leads to an improved value of the dissociation energy D_0^N=1 of ortho-H_2 that has, for the first time, reached a level of uncertainty that is three times smaller than the
more » ... ion of about 1 MHz resulting from the finite size of the proton. The new result of 35999.582834(11) cm^-1 is in remarkable agreement with the theoretical result of 35999.582820(26) cm^-1 obtained in calculations including high-order relativistic and quantum electrodynamics corrections, as reported in the companion article (M. Puchalski, J. Komasa, P. Czachorowski and K. Pachucki, submitted). This agreement resolves a recent discrepancy between experiment and theory that had hindered a possible use of the dissociation energy of H_2 in the context of the current controversy on the charge radius of the proton.
doi:10.1103/physrevlett.122.103002 fatcat:pg77tdfvurbmhkkupsegu6dhti