On the simultaneous ionization-excitation of the OII(λ834 Å) resonance transition by electron impact on atomic oxygen

Abstract

Laboratory cross-section data on the excitation of the OII(2s 2p 4 4P → 2s 2 2p 3 4S; λ834 Å) resonance transition and on the production of O + and O 2+ ions by electron impact on atomic oxygen are used to show that the ratio σ(λ834 A ̊ ) σ(O + + O 2+) is nearly constant for incident electron energies > 50 eV. Under auroral conditions, the total electron-ion pair production rate from electron impact on O can be inferred from λ834 Å volume emission rate measurements using the result that η(O + + O 2+) $ ̃ 8.4η(λ834 A ̊ ) . These findings, along with earlier work on the simultaneous ionization-excitation of the 1 Neg (0,0) band of N 2 + and the 1 Neg (1, 0) band of O + 2, allow the specific ionization rates for the principal atmospheric constituents (O +, O + 2, N + 2), for the multiply-ionized species (O 2+, O 2+ 2, N 2+ 2), and for the dissociatively produced atomic ions to be inferred in aurora from remote satellite observations.