I2(B) formation, in the oxygen-iodine laser medium

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(1)Sigma,v'=0) -> O-2(X-3 Sigma,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(1)Delta, v'=1) were detected using IR emission spectroscopy. The measured relative density of O-2(a(1)Delta;v'=1) for the conditions of a typical oxygen-iodine laser medium amounted to similar 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(1)Delta,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)Sigma) does not excite I-2(B) to a significant degree.