Studies of nonequilibrium vibrational kinetics of carbon monoxide and nitric oxide in optical pumping experiments.

摘要

This dissertation presents the design, analysis, theoretical interpretation, and conduct of optical pumping experiments to study molecular energy transfer processes in carbon monoxide and nitric oxide. The vibrational modes of CO and NO are excited by resonance absorption of CO laser radiation and subsequent vibration-to-vibration (V-V) pumping in CO-Ar-He and NO-Ar mixtures in a cell. Ionization of CO molecules at high vibrational levels occurs in the laser beam region. The vibrational distribution function (VDF) of CO in the cell is measured by infrared emission spectroscopy. It is demonstrated that a definite correlation exists between the induced current and the high vibrational level populations. It is concluded that the ionization occurs in collisions of two vibrationally excited CO molecules. An ionization rate constant of k{dollar}sb{lcub}rm i{rcub}{dollar} = (8 {dollar}pm{dollar} 5) {dollar}times{dollar} 10{dollar}sp{lcub}-15{rcub}{dollar} cm{dollar}sp3{dollar}/s is inferred from the VDF measurements. The effect of vibration-to-electron (V-e) coupling is measured in the experiment for the first time.; The NO fluorescence in the infrared and in the ultraviolet is analyzed. Quantitative analysis of the NO IR overtone spectrum, {dollar}Delta{dollar}v = 2, allows inference of the NO(X{dollar}sp2Pi{dollar}) VDF up to vibrational level v = 15. It is shown that the mechanism of vibrational excitation is anharmonic V-V pumping. In particular, the higher vibrational levels, v {dollar}ge{dollar} 8, are populated by near-resonant V-V exchange processes. It is suggested that the electronically excited NO molecules in A{dollar}sp2Sigma{dollar} and B{dollar}sp2Pi{dollar} states, which are observed, can be produced both by resonant vibration-to-electronic (V-E) energy transfer processes and in energy pooling reactions. Previous rate measurement experiments in NO are analyzed and discussed in light of the present data, and further state-resolved measurements are proposed.; Kinetics of spatially nonhomogeneous, vibrationally excited gas flows is theoretically discussed. The corrections due to diffusion and the vibration-to-electronic (V-E) energy transfer to the vibrational distribution function (VDF) and to the vibrational energy balance are obtained. It is shown that non-local diagnostics may significantly influence the inferred distribution function, as has been previously reported in experiments. A new two-dimensional kinetic model of vibrationally nonequilibrium flows is developed. The comparison of the model calculations with experiments shows reasonable agreement within the applicability of the gas flow model.