KINETIC-STUDY OF E-BEAM EXCITED AR-CO2 MIXTURE

Dissociation of the CO2 molecule by collision with metastable argon (3P2) was shown a few years ago to lead to the excitation of the first vibrational levels of the metastable (a 3π) state of CO and the aim of the present work is to investigate the possibility of using this transfer reaction to obtain population inversions of the a 3Π→X 1Σ transition of the CO molecule. Because of the low CO* fluorescence intensity level, we only performed an indirect kinetic study of e-beam excited Ar-CO2 mixture. Using N2(c→B)(λ=337 nm) fluorescence emission as an Ar* population tracer in Ar-CO2-N2 mixture, we measured the kinetic constants relevant to Ar-CO2 mixture. It is shown that for certain Ar-CO2 mixtures, 50% of the initial excitation created by the electron gun is transferred to Ar* atoms and then disappears in Ar*+CO2 collisions. A comparative study of the instantaneous fluorescence intensity of CO* (a 3π) in Ar-CO2 mixture with that of N2(C) in Ar*-N 2 mixture showed that the branching ratio of the Ar*+CO 2→CO* (a 3π) reaction was, at most, 10%. Consequently, the largest population efficiency (5%) does not permit laser oscillation in our experiment. Furthermore, the feasibility of such a laser depends on eventual direct population of ground state level by Ar*+CO 2 reaction. © 1980 American Institute of Physics.