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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 109, A03302, doi:10.1029/2003JA010132, 2004

Dissociative recombination of N₂ ⁺, O₂ ⁺, and NO⁺: Rate coefficients for ground state and vibrationally excited ions

Clint H. Sheehan

Department of Physics, Ouachita Baptist University, Arkadelphia, Arkansas, USA

J.-P. St.-Maurice

Department of Physics and Astronomy, University of Western Ontario, London, Ontario, Canada

Abstract

We review recent advances in the study of the dissociative recombination of molecular ions with electrons with a primary emphasis on experimental studies. In particular, we focus on previous experimental measurements of recombination rates for N₂ ⁺, O₂ ⁺, and NO⁺ ions. In the context of this review, we present temperature dependent rate coefficients from recent merged beam studies of the dissociative recombination of N₂ ⁺, O₂ ⁺, and NO⁺ ions with electrons. Identifying underlying physical differences between the various experimental techniques enables a discussion of the effects of vibrational excitation on the dissociative recombination of these major ionospheric species of ions. For T < 1200 K, we conclude that the recombination rates for N₂ ⁺, O₂ ⁺, and NO⁺ ions in the ground electronic and vibrational states respectively are 2.2 × 10⁻⁷ (T_e/300)^−0.39 cm³ s⁻¹, 1.95 × 10⁻⁷(T_e/300)^−0.70 cm³ s⁻¹, and (3.5 ± 0.5) × 10⁻⁷(T_e/300)^−0.69 cm³ s⁻¹. Vibrational excitation is shown to play a significant role in laboratory measurements of these recombination rates. For each of these species, vibrationally excited ions yielded a lower recombination rate than the ground state. We also discuss the recombination of these species of ions for T > 1200 K.

Received 10 July 2003; accepted 27 January 2004; published 13 March 2004.

Index Terms: 2419 Ionosphere: Ion chemistry and composition (0335); 0317 Atmospheric Composition and Structure: Chemical kinetic and photochemical properties; 0335 Atmospheric Composition and Structure: Ion chemistry of the atmosphere (2419, 2427); 2407 Ionosphere: Auroral ionosphere (2704); 2459 Ionosphere: Planetary ionospheres (5435, 5729, 6026, 6027, 6028).

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Citation: Sheehan, C. H., and J.-P. St.-Maurice (2004), Dissociative recombination of N₂ ⁺, O₂ ⁺, and NO⁺: Rate coefficients for ground state and vibrationally excited ions, J. Geophys. Res., 109, A03302, doi:10.1029/2003JA010132.

Copyright 2004 by the American Geophysical Union.