Ionization and Dissociation Energies of Molecular Hydrogen
Year: 2026
Type: article
Abstract: Molecular hydrogen ( H 2 ) is the simplest neutral molecule, and its ionization and dissociation energies are key benchmarks for testing first-principles calculations of nonadiabatic, relativistic, quantum-electrodynamic, and finite-nuclear-size effects in molecules. To obtain improved H 2 ionization and dissociation energies, we performed precision measurements of 15 transition frequencies in para- H 2 . They connect the X Σ g + 1 ( v = 0 , N = 0 ) ground state, the long-lived EF 1 Σ g + ( v = 0 , N = 0 ) excited state, and several high members of the n p and n d Rydberg series with principal quantum number n in the range between 48 and 70. These data lead to a 5 times more accurate value of the ionization energy of the ground state of para- H 2 , equivalent to a relative frequency accuracy of 5 × 10 − 11 . Combined with a global network analysis of 45 energy intervals in para- and ortho- H 2 that have been measured in the past three decades, we obtain statistically robust values for the ionization energy [ E I ( 0 , 0 ) / ( h c ) = 124 417.491 157 3 ( 58 ) cm − 1 ] and the dissociation energy [ D 0 N = 0 = 36 118.069
Source: Physical Review X
DOI: 10.1103/42c4-pc1s
Authors: Ioana Doran, Charlaine Roth, Nicolas Hölsch, Maximilian Beyer, Andrés Martínez de Velasco, Vincent Barbé, Mathieu Collombon, Elmer Gründeman, Julian J. Krauth, Jinjun Liu, Josef A. Agner, Urs Hollenstein, Andreas Osterwalder, Hansjürg Schmutz, Daniel Sprecher, Andrea Wüest, Wim Ubachs, Christian Jungen, Kjeld S. E. Eikema, Frédéric Merkt
Language: English
Topic: Atomic and Molecular Physics
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,200
Funders: European Commission, Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Eidgenössische Technische Hochschule Zürich, Nederlandse Organisatie voor Wetenschappelijk Onderzoek, Uniwersytet Warszawski, Horizon 2020 Framework Programme, HORIZON EUROPE Framework Programme, European Research Council
OpenAlex ID: W7204842228