Collisional Quenching of Highly Excited H2 due to H2 Collisions

Yier Wan, B. H. Yang, P. C. Stancil, N. Balakrishnan, Nikhil J. Parekh, R. C. Forrey

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15 Scopus citations


Rate coefficients for pure rotational quenching in H21 = 0, j 1) + H22 = 0, j 2) collisions from initial levels of j 1 = 2-31 (j 2 = 0 or 1) to all lower rotational levels are presented. We carried out extensive quantum mechanical close-coupling calculations based on a recently published H2-H2 potential energy surface (PES) developed by Patkowski et al. that has been demonstrated to be more reliable than previous work. Rotational transition cross sections with initial levels of j 1 = 2-14, 18, 19, 24, and 25 were computed for energies ranging from 10-6 to 1000 cm-1, while the coupled-states approximation was adopted from 2000 to 20,000 cm-1. The corresponding rate coefficients were calculated for the temperature range 10-5 ≤ T ≤ 10,000 K. Scaling methods based on the ultra-cold data (10-5-1 K) were used to estimate rate coefficients for all other intermediate rotational states. Comparisons with previous work that adopted different PESs show small discrepancies at high temperatures and in low-energy resonance regions. The astrophysical applications of the current results are briefly discussed, including the rotational H2 critical densities due to para-H2 and ortho-H2 collisions.

Original languageEnglish (US)
Article number132
JournalAstrophysical Journal
Issue number2
StatePublished - Aug 1 2018

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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