Chemiluminescence from Al+O3: Perturbations, populations, and vibrational analysis for the AlO A 2Π–X 2Σ+ transition

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Abstract
As a complement to an earlier study of the AlO B 2Σ+–X 2Σ+ emission system, the A 2Πi–X 2Σ+ chemiluminescence resulting from the reaction Al+O3→AlO*+O2 has been investigated. It is found that the constants extracted for the A 2Πi state by McDonald and Innes adequately describe the vibrational structure of this state to high (∼29) vibrational levels, the behavior being indicative of a Morse oscillator. Perturbations previously observed in the X 2Σ+ state are explicitly analyzed in terms of A 2 Π1/2–X 2Σ+ spin–orbit interactions, and a comparison with A 2Π1/2–B 2Σ+ perturbations is made. Approximate populations Nv′ for the A 2Πi vibrational levels are determined; the population distribution is dramatically non-Boltzmann, peaking at an energy just below that corresponding to the v=0 level of the B 2Σ+ state. This peaking is explained in terms of efficient collisional transfer from the A state to the B state.