Dissociation energy of the hydrogen molecule at 10$^{-9}$ accuracy

TL;DR

This paper reports an ultra-precise measurement of the hydrogen molecule's dissociation energy, achieving 10$^{-9}$ accuracy, providing a benchmark for testing advanced theoretical calculations including relativistic and quantum electrodynamics effects.

Contribution

The study presents the most accurate experimental determination of the hydrogen molecule's dissociation energy, surpassing previous results by over an order of magnitude and challenging existing theoretical models.

Findings

Dissociation energy of H₂ measured with 10$^{-9}$ precision.

Results serve as a benchmark for relativistic and QED calculations.

Experimental data exceeds accuracy of prior measurements.

Abstract

The ionization energy of ortho-H$_2$ has been determined to be $E^\mathrm{o}_\mathrm{I}(\mathrm{H}_2)/(hc)=124\,357.238\,062(25)$ cm$^{-1}$ from measurements of the GK(1,1)--X(0,1) interval by Doppler-free two-photon spectroscopy using a narrow band 179-nm laser source and the ionization energy of the GK(1,1) state by continuous-wave near-infrared laser spectroscopy. $E^\mathrm{o}_\mathrm{I}$(H$_2$) was used to derive the dissociation energy of H$_2$, $D^{N=1}_{0}$(H$_2$), at $35\,999.582\,894(25)$ cm$^{-1}$ with a precision that is more than one order of magnitude better than all previous results. The new result challenges calculations of this quantity and represents a benchmark value for future relativistic and QED calculations of molecular energies.