Rate Parameters for Electronic Excitation of Diatomic Molecules: NO Radiation

Abstract

This is one of an ongoing series of papers on collisional excitation of electronic states in N(2), O(2), NO, CO, CN, and N(2)(+). In this paper, NO radiation observed in the test section of an arcjet wind tunnel is studied. In the experiments, NO gamma and delta were seen, beta was not seen, and e was seen to be very weak. NO radiation is calculated with the use of the code SPRADIAN07 to explain the measured spectra. It was found that inverse predissociation is mainly responsible for the population of the NO C(2)Pi, state during recombination of N and O atoms. The population of the NO A(2)Sigma(+) state is mostly due to the radiative decay from the NO C(2)Pi state. The NO D(2)Sigma(+) state is excited from the C(2)Pi(r) state by collisions. The NO B(2)Pi(r) state is populated by complicated collisional transition paths by passing through the intermediate states alpha(4)Pi(r) and b(4)Sigma(-). These interpretations at least qualitatively explain the experimental data. Electronic excitation temperature is only remotely related to electron temperature.