The formation of SiH

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.