Pressure effects on bimolecular recombination and unimolecular dissociation reactions

The treatment of pressure effects on bimolecular recombinations and unimole cular dissociations is discussed. The analysis of recombination and dissoci ation reactions is made by showing how the nonequilibrium energy (E) and an gular momentum (J)-dependent steady-state population distribution functions for the two reactions are related to each other and to the equilibrium pop ulation distribution function at the given E and J. As a special case a str ong collision model is then used for the collisional rotational angular mom entum transfer, and a ladder model for the collisional energy transfer. An analytical result is obtained for states below the dissociation threshold. The extension to recombinations with two exit channels is described, for ap plication to ozone formation and isotopic effects. (C) 2001 American Instit ute of Physics.