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 S,n'=0) → O 2 (X 3 S,n''=0) band as a reference, I 2 (B) relative number densities were assessed by measuring the I 2 (B,n')→ I 2 (X,n") emission intensities. Vibrationally excited singlet oxygen molecules O 2 (a 1 D, n'=1) were detected using IR emission spectroscopy. The measured relative density of O 2 (a 1 D,n'=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 1 D,n'). 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 S) does not excite I 2 (B) to a significant degree.