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Effect of Vibrational Excitation on Rate Parameters of Atmospheric Reactions.

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Final rept. 3 Nov 83-2 May 87,

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In the Earths thermosphere, under conditions of low pressure and high solar flux, metastable atomic and molecular species acquire increased importance, particularly under conditions of natural or artificial perturbation. For molecules, the excitation can be either electronic or vibrational, and it is estimated that approx 40 of thermospheric solar UV energy is channeled through metastables. The effect of vibrational excitation on the reactivity of a given species is poorly understood at present. The purpose of this project was to obtain relevant data, both for direct input to models of perturbated atmospheres, and to yield new insight into the effects of vibrational excitation. This study has concentrated on the reactions of the lowest electronically excited state of N2, the metastable N2 A3 Sigma sub u state, in its lowest seven vibrational levels. THe reagents 02, NO, CO, N20 and C2H4 were chosen for their atmospheric relevance, but also exhibit an interesting variety of properties. The study was extended to include two inefficient electronic quenchers, CH4 and CF4, which are shown to deactivate N2A principally via vibrational relaxation. Preliminary data on two other inefficient quenchers, H2 and D2, are also included in this report, as are results on product analysis of the related reaction of N2A with O3p atoms.

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  • Atmospheric Physics
  • Physical Chemistry

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