Recombination of H 2 by Raman Association in the Early Universe

Abstract

We investigate the contribution that Raman association makes to H2 production in the early universe at redshifts 10 ≤ z ≤ 104. The Raman process involves inelastic scattering of electromagnetic radiation off two colliding hydrogen atoms, taking away kinetic and binding energy and leaving bound H2. We calculate the inelastic cross sections and rate coefficients for this process and determine the Raman association rate in the cosmic background radiation field present during the early stages of the universe. A comparison with other H2-forming reactions is made.