Improved Ionization and Dissociation Energies of the Deuterium Molecule

TL;DR

This paper reports highly precise measurements of the ionization and dissociation energies of the deuterium molecule, providing a stringent test of quantum electrodynamics and opening pathways for nuclear charge radius determination.

Contribution

The study presents the most accurate experimental values for D$_2$ ionization and dissociation energies, aligning well with advanced ab initio quantum calculations and enhancing QED tests in molecules.

Findings

D$_2$ ionization energy measured as 124,745.393739(26) cm$^{-1}$.

D$_2$ dissociation energy determined as 36,748.362282(26) cm$^{-1}$.

Results agree within 1.6 sigma with theoretical calculations.

Abstract

The ionization energy of 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 $E_\mathrm{I}(\mathrm{D}_2)=124\,745.393\,739(26)$ \wn. From this value, the dissociation energy of D$_2$ is deduced to be $D_0$(D$_2$) = 36\,748.362\,282(26) \wn, representing a 25-fold improvement over previous values, and found in good agreement (at $1.6\sigma$) with recent ab initio calculations of the 4-particle nonadiabatic relativistic energy and of quantum-electrodynamic corrections up to order $m\alpha^6$. This result constitutes a test of quantum electrodynamics in the molecular domain, while a perspective is opened to determine nuclear charge radii from molecules.