VIBRATIONAL AND ELECTRONIC EXCITATION OF NITRIC-OXIDE IN OPTICAL-PUMPING EXPERIMENTS

Nitric oxide is vibrationally excited in a flowing gas mixture of NO-A r using resonance absorption of single-line CO laser radiation. The fl uorescence in the infrared and in the ultraviolet is analyzed under st eady-state pumping conditions. Quantitative analysis of the NO IR over tone spectrum, DELTAupsilon=2, allows inference of the vibrational dis tribution function of the X 2PI ground state up to vibrational level u psilon=15. It is shown that the mechanism of vibrational excitation is anharmonic vibration-vibration pumping. In particular, the higher vib rational levels, upsilon greater-than-or-equal-to 8, are populated by near-resonant vibration-to-vibration exchange processes. It is suggest ed that the electronically excited NO molecules in A 2SIGMA and B 2PI States, which are observed, can be produced both by resonant vibration -to-electronic energy transfer processes and in energy pooling reactio ns. Previous rate measurement experiments in NO are analyzed and discu ssed in light of the present data, and further state-resolved measurem ents are proposed.