Benchmarking theory with an improved measurement of the ionization and dissociation energies of H${}_2$

Abstract

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 ${}^1{\Sigma }_g^{+}(v=0,N=1)$ 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 contribution 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.

References in corpus (1)

• Complete ${\alpha }^{6}m$ corrections to the ground state of H${}_2$

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