IMPROVEMENT OF THE DISSOCIATION ENERGY OF THE HYDROGEN MOLECULE (PART ONE)

The dissociation energy (D$_0$) of ortho H$_2$ is a benchmark value in quantum chemistry, with recent QED calculations now approaching accuracies achievable in simple atoms. A precision measurement of the GK-X molecular transition, in combination with other precision measurements (see also part two), provides an improved value for D$_0$.$[1,2]$ The GK-X transition is excited through Doppler-free two-photon spectroscopy using 179-nm radiation, based on frequency up-conversion using a special KBBF crystal. The optical frequency of the fundamental (716 nm), which is the output of a narrowband pulsed Ti:Sa laser system, is locked to a frequency comb. This enables accuracies at the sub-MHz level, leading to an order-of-magnitude improvement for D$_0$ to the 10$^{-9}$ level of accuracy. The comparison of this accurate experimental result with the best calculations may provide a test of the Standard Model of Physics.$[3]$\\ \\ $[1]$ D. Sprecher, Ch. Jungen, W. Ubachs and F. Merkt, Faraday Discussions 150, 51-70 (2011)\\ $[2]$ W. Ubachs, J.C.J. Koelemeij, K.S.E. Eikema and E.J. Salumbides, J. Mol. Spectr. 320, 1-12 (2016)\\ $[3]$ J. Liu, E. J. Salumbides, U. Hollenstein, J. C. J. Koelemeij, K. S. E. Eikema, W. Ubachs and F. Merkt, J. Chem. Phys. 130 (17), 174306 (2009)\

IMPROVEMENT OF THE DISSOCIATION ENERGY OF THE HYDROGEN MOLECULE (PART ONE)

The dissociation energy (D$_0$) of ortho H$_2$ is a benchmark value in quantum chemistry, with recent QED calculations now approaching accuracies achievable in simple atoms. A precision measurement of the GK-X molecular transition, in combination with other precision measurements (see also part two), provides an improved value for D$_0$.$[1,2]$ The GK-X transition is excited through Doppler-free two-photon spectroscopy using 179-nm radiation, based on frequency up-conversion using a special KBBF crystal. The optical frequency of the fundamental (716 nm), which is the output of a narrowband pulsed Ti:Sa laser system, is locked to a frequency comb. This enables accuracies at the sub-MHz level, leading to an order-of-magnitude improvement for D$_0$ to the 10$^{-9}$ level of accuracy. The comparison of this accurate experimental result with the best calculations may provide a test of the Standard Model of Physics.$[3]$\\ \\ $[1]$ D. Sprecher, Ch. Jungen, W. Ubachs and F. Merkt, Faraday Discussions 150, 51-70 (2011)\\ $[2]$ W. Ubachs, J.C.J. Koelemeij, K.S.E. Eikema and E.J. Salumbides, J. Mol. Spectr. 320, 1-12 (2016)\\ $[3]$ J. Liu, E. J. Salumbides, U. Hollenstein, J. C. J. Koelemeij, K. S. E. Eikema, W. Ubachs and F. Merkt, J. Chem. Phys. 130 (17), 174306 (2009)\

Improved ionization and dissociation energies of the deuterium molecule

The ionization energy of D2 has been determined experimentally from measurements involving two-photon Doppler-free vacuum-ultraviolet pulsed laser excitation and near-infrared continuous-wave laser excitation to yield EI(D2)=124745.393739(26) cm-1. From this value, the dissociation energy of D2 is deduced to be D0(D2)=36748.362282(26) cm-1, representing a 25-fold improvement over previous values, and it was found to be in good agreement (at 1.6s) with recent ab initio calculations of the four-particle nonadiabatic relativistic energy and of quantum-electrodynamic corrections up to order ma6. This result constitutes a test of quantum electrodynamics in the molecular domain, while a perspective is opened to determine nuclear charge radii from molecules.ISSN:1094-1622ISSN:0556-2791ISSN:1050-294

Ionization and dissociation energies of HD and dipole-induced

ISSN:1094-1622ISSN:0556-2791ISSN:1050-294