Experimental and theoretical study of distribution of $O2$ molecules over vibrational levels in $O2(a 1Δg)–I$ mixture Available to Purchase

The vibrationally excited oxygen in $O2(a 1Δg)–I$ mixture was detected by emission spectroscopy. The analysis of a luminescence spectra of oxygen molecules on $O2(b 1Σg+,v′)→O2(X 3Σg−,v″)$ transitions has shown that vibrationally excited $O2(b 1Σg+)$ molecules up to $v=5$ are generated in the active medium of chemical oxygen–iodine laser (COIL). The highest values of relative $O2(b 1Σg+,v=1)$ population of 22±2% and $O2(b 1Σg+,v=2)$ of 10±3.5% are reached for $I2$ content in an oxygen flow ≈1%. It is shown theoretically that the relative populations of $O2(X 3Σg−),$ $O2(a 1Δg),$ and $O2(b 1Σg+)$ molecules at the first and the second vibrational levels are approximately equal because of fast EE energy exchange between oxygen molecules. Up to 20% of oxygen molecules in COIL active medium are vibrationally excited. Comparison of intensities of $O2(b 1Σg+,v′)→O2(X 3Σg−,v″)$ bands has demonstrated that a few percent of $O2(b 1Σg+,v)$ molecules are vibrationally excited with $v=3,$ 4, or 5. It is suggested that the following pooling reaction forms them: $O2(a 1Δg,v=i)+I(2P1/2)→O2(b 1Σg+,v′=i+2)+I(2P3/2),$ where $i=1,$ 2, or 3.