The Radiative Association of He + and He and H + and H
Abstract
The rate coefficient for the radiative association of He+ and He to form He(2+) is determined for temperatures T between 20 K and 500,000 K. It can be represented by a given relation to within 25 percent applicable up to 50,000 K. It is about an order of magnitude less than the rate coefficient for the radiative association of H(+) and H to form H(2+). Cross sections for the He(2+) and H(2+) reactions calculated using a fully quantum-mechanical method reveal weak resonance features at low energies. Implications of the He(+) + He radiative association process are discussed briefly in connection with the chemistry of supernova ejecta, planetary nebulae, and the early universe.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 1993
- DOI:
- 10.1086/173113
- Bibcode:
- 1993ApJ...414..672S
- Keywords:
-
- Association Reactions;
- Helium Ions;
- Interstellar Chemistry;
- Molecular Ions;
- Cosmology;
- Hydrogen Ions;
- Planetary Nebulae;
- Supernova Remnants;
- Supernova 1987a;
- Atomic and Molecular Physics