Excitation of CN violet (B 2Σ+−X 2Σ+) and red (A 2Πi−X 2Σ+) bands by reaction of Ar and Xe metastable atoms with CN-containing compounds

Abstract

The vibrational, and in some cases rotational, populations of the CN (A 2Πi) and (B 2Σ+) states produced by the dissociative excitation reactions of metastable argon and xenon atoms with HCN, ICN, and BrCN have been measured. Emission from the D, E, and F states of CN were observed from Ar(3P0,2) with BrCN. Anomalously high intensities from perturbed rotational levels of CN (B 2Σ+; v′ = 0, 11, 14) were found, and only the perturbed levels are produced from CNBr and CNI. The interaction of metastable argon atoms with BrCN and ICN gave excitation to v′ = 20 of CN (B 2Σ+) with a population inversion for v′ > 11 relative to lower levels. Extremely high rotational excitation of CN (B 2Σ+; v′ = 0, 1, 2) resulted from the interaction of Xe(3P2) with BrCN and ICN. The spectroscopic observations provide extensive detail and illustrate the complexity of these dissociative excitation reactions. In addition to a short discussion of the mechanism of interaction between the metastable atoms and CN compounds, some comments are offered concerning the spectroscopy of the CN red and violet emissions. Investigation of the electronic quenching of CN (B) emission showed an unusually high quenching rate for v′ = 11 by CNBr or CNI.