Rate Parameters for Electronic Excitation of DiatomicMolecules: NO Radiation

Abstract

This is the fourth of a four-part paper on collisional excitation of electronic states in N2, O2, NO, CO, CN, and N + . In this paper, NO radiation observed in the test section of an arcjet wind tunnel is studied. In the experiments, NO and were seen, was not seen, and 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 r state ( ) during recombination of N and O atoms. The population of the NO A 2 + state ( ) is mostly due to the radiative decay from the NO C 2 r state. The NO D 2 + state () is excited from the C 2 r state by collisions. The NO B 2 r state ( ) is populated by complicated collisional transition paths by passing through the intermediate states a 4 r and b 4 − . These interpretation at least qualitatively explains the experimental data. Electronic excitation temperature is only remotely related to electron temperature.