Astron. Astrophys. Suppl. Ser. 142, 107-112

The formation of SiH⁺, PH⁺, and SH⁺ by radiative association

P.C. Stancil^1,2 - K. Kirby³ - J.-P. Gu⁴ - G. Hirsch⁴ - R.J. Buenker⁴ - and A.B. Sannigrahi⁵

Send offprint request: P.C. Stancil

1 - Physics Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6372, U.S.A.
e-mail: stancil@mail.phy.ornl.gov
2 - Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996-1200, U.S.A.
3 - Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, U.S.A.
e-mail: kkirby@cfa.harvard.edu
4 - Theoretische Chemie, Bergische Universität-Gesamthochschule Wuppertal, Gaußstr. 20, D-42097 Wuppertal, Germany
e-mail: jgu@ist.ucf.edu, buenker@wrcs1.urz.uni-wuppertal.de
5 - Department of Chemistry, Indian Institute of Technology, Kharagpur 721 302, India

Received July 19; accepted November 23, 1999

Abstract:

Cross sections for the radiative association of Si⁺, P⁺, and S⁺ with atomic hydrogen to form the diatomic molecular ions SiH⁺, PH⁺, and SH⁺, respectively, are presented. The results are obtained using fully quantum-mechanical techniques and utilize ab initio molecular data calculated with the multireference single- and double-excitation configuration-interaction (MRD-CI) method. Thermal rate coefficients are presented and applications of the results to diffuse interstellar clouds are discussed.

Key words: molecular processes -- ISM: molecules