Isotopomer fractionation in the UV photolysis of N_2O: 2. Further comparison of theory and experiment

Abstract

Wavelength-dependent fractionation of various isotopomers in the photodissociation of N_2O is studied. The absorption cross sections are calculated by a time-independent reflection principle, related to the Prakash et al. (2005) treatment but now with an inclusion of the NN stretching coordinate and both the 2A′ and 1A″ electronic excited states. The added 1A″ state is found to have little effect on both the absorption cross section and the fractionation. The improvements include more physical details in the photodissociation of N_2O, while maintaining an advantage of a treatment in the work by Prakash et al. (2005) that was not computationally intensive. The present calculated fractionation, without a significant adjustable parameter, gives good agreement with experiments in the absorption cross section in the low-energy region, the important region for the experimentally observed isotopic fractionation.