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Title: Depopulation of metastable helium by radiative association with hydrogen and lithium ions

Depopulation of metastable He(2{sup 3}S) by radiative association with hydrogen and lithium ions is investigated using a fully quantal approach. Rate coefficients for spontaneous and stimulated radiative association of the HeH{sup +}, HeD{sup +}, and LiHe{sup +} molecular ions on the spin-triplet manifold are presented as functions of temperature considering the association to rotational-vibrational states of the lowest triplet electronic states a {sup 3}Σ{sup +} and b {sup 3}Σ{sup +} from the continuum states of the b {sup 3}Σ{sup +} electronic state. Evaluation of the rate coefficients is based on highly accurate quantum calculations, taking into account all possible state-to-state transitions at thermal energies (for spontaneous association) or at higher background energies (stimulated association). As expected, calculations show that the rate coefficients for radiative association to the a state are several orders of magnitude larger than the one for the b state formation. A noticeable effect by blackbody background radiation on the radiative association is only obtained for the b → b process. Aspects of the formation and abundance of the metastable HeH{sup +}(a {sup 3}Σ{sup +}) in astrophysical environments are briefly discussed.
Authors:
;  [1] ;  [2]
  1. Charles University in Prague, Faculty of Mathematics and Physics, Department of Chemical Physics and Optics, Ke Karlovu 3, CZ-12116 Prague 2 (Czech Republic)
  2. Max-Planck Institute of Astrophysics, Postfach 1371, D-85741 Garching (Germany)
Publication Date:
OSTI Identifier:
22348038
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 782; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; BACKGROUND RADIATION; EVALUATION; HELIUM; HYDROGEN; MOLECULAR IONS; SPIN; TEMPERATURE DEPENDENCE; TRIPLETS; VIBRATIONAL STATES