Excitation of H2 at large internuclear separation: outer well states and continuum resonances

T. M. Trivikram, E. J. Salumbides, Ch Jungen, W. Ubachs*

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


Bound and free quantum resonances of molecular hydrogen exhibiting wave-function density at large internuclear separation, (Formula presented.) 4–5 a.u., are excited via multi-step laser spectroscopy. Highly excited vibrational levels of H (Formula presented.) are prepared via two-photon UV-photolysis of H (Formula presented.) S. Subsequent two-photon Doppler-free precision measurements are performed connecting (Formula presented.) levels with (Formula presented.) outer-well levels. Detection and spectroscopic labelling of the quantum states is assisted by further laser excitation into the auto-ionisation continuum employing a third UV-laser. Level energies of high rotational states ((Formula presented.)) in the outer-well state (Formula presented.) are accurately determined. The three-laser study demonstrates a method for probing resonances in the H (Formula presented.) ionisation continuum with wave-function density at large internuclear separation (Formula presented.) 4–5 a.u., large angular momenta J, and energy range 131,100–133,000 cm −1, a hitherto unexplored territory.

Original languageEnglish
Pages (from-to)2961-2971
Number of pages11
JournalMolecular Physics
Issue number21
Early online date29 Mar 2019
Publication statusPublished - 2 Nov 2019


  • Molecular hydrogen
  • autoionisation
  • complex resonance
  • laser spectroscopy
  • outer-well states


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