Master Equation Studies of the Collisional Excitation and Dissociation of H 2 Molecules by H Atoms

The master equation for collisional excitation of H₂ by H atoms is solved over a temperature range of T = 450-45,000 K and a density range of nH = 10⁻³-10⁹ cm⁻³. Radiative transitions due to quadrupole emission and dissociative tunneling are included explicitly. The resulting nonequilibrium steady state populations of the (υ, j) states of H₂ are determined and then used to calculate the rate coefficients for ortho-para interconversion, collisional dissociation, dissociative tunneling, and cooling. The density and temperature dependences of these rates are discussed and parameterized. Comparisons with previous estimates are made.