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.