Excitation and Deexcitation of Vibration in N2 by Oxygen Atoms
STANFORD RESEARCH INST MENLO PARK CA
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The earths upper atmosphere continuously emits infrared radiation. Some of this radiation is powered by the energy stored in vibrationally excited nitrogen, and it has been suggested that this is produced when nitrogen quenches Osinglet D. In this reaction the 1.96 eV electronic excitation of Osinglet D is transferred to vibrational and rotational energy of the nitrogen and kinetic energy. Because no measurements of the fraction that appears as vibrational energy were available, the first task of the authors research program was to measure this fraction, using Raman spectroscopy to determine the population of N2v1 that is produced. The experimental findings support the theoretical estimate of the Osinglet D vibrational energy. The authors obtain an efficiency of 8.3 plus or minus 6.5 for the conversion of Osinglet D electronic energy to N2 vibrations. Once produced, the vibrationally excited nitrogen is deexcited only by collisions. Above 125 km, the vibrationally excited nitrogen is removed by diffusion, by electron quenching, and by vibrational-translational energy exchange with Otriplet P. The reaction rate for the process was found. Results are reported for N2-1 CO, N2-5 CO, and N2- 5 O2-1 CO mixtures. An infrared-tracer technique was used.
- Atmospheric Physics
- Atomic and Molecular Physics and Spectroscopy