I_2(B) formation in the oxygen-iodine laser medium

摘要

The mechanism by which I_2(B) is excited in the chemical oxygen-iodine laser was studied by means of emission spectroscopy. Using the intensity of the O_2(b~1Σ,v'=0) → O_2(X~3Σ,v"=0) band as a reference, I_2(B) relative number densities were assessed by measuring the I_2(B,v')→ I_2(X,v") emission intensities. Vibrationally excited singlet oxygen molecules O_2(a~1Δ, v'=1) were detected using IR emission spectroscopy. The measured relative density of O_2(a~1Δ,v'=1) for the conditions of a typical oxygen-iodine laser medium amounted to ～15% of the total O_2 content. Mechanisms for I_2(B) formation were proposed for both the I_2 dissociation zone and the region downstream of the dissociation zone. Both pumping mechanisms involved electronically excited molecular iodine I_2(A', A) as an intermediate. It has been suggested that, in the dissociation zone, the I_2 A', and A states are populated in collisions with vibrationally excited singlet oxygen molecules O_2(a~1A,v'). In the region downstream of the dissociation zone the intermediate states are populated by iodine atom recombination process. I_2(B) is subsequently formed in collisions of I_2(A',A) with singlet oxygen. We also conclude that I_2(B) does not participate measurably in the I_2 dissociation process and that energy transfer from O_2(b~1 Σ) does not excite I_2(B) to a significant degree.