Improved ionization and dissociation energies of the deuterium molecule
J. Hussels, Nicolas Hölsch, Cunfeng Cheng, E. J. Salumbides, Hendrick L. Bethlem, K. S. E. Eikema, Ch. Jungen, Maximilian Beyer, F. Merkt, W. Ubachs
Abstract
The ionization energy of ${\mathrm{D}}_{2}$ 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 ${E}_{\mathrm{I}}({\mathrm{D}}_{2})=124\phantom{\rule{0.16em}{0ex}}745.393\phantom{\rule{0.16em}{0ex}}739(26) {\mathrm{cm}}^{\ensuremath{-}1}$. From this value, the dissociation energy of ${\mathrm{D}}_{2}$ is deduced to be ${D}_{0}\phantom{\rule{0.16em}{0ex}}({\mathrm{D}}_{2})=36\phantom{\rule{0.16em}{0ex}}748.362\phantom{\rule{0.16em}{0ex}}282(26) {\mathrm{cm}}^{\ensuremath{-}1}$, representing a 25-fold improvement over previous values, and it was found to be in good agreement (at $1.6\ensuremath{\sigma}$) with recent ab initio calculations of the four-particle nonadiabatic relativistic energy and of quantum-electrodynamic corrections up to order $m{\ensuremath{\alpha}}^{6}$. This result constitutes a test of quantum electrodynamics in the molecular domain, while a perspective is opened to determine nuclear charge radii from molecules.