Quantitative determination of singlet oxygen density and temperature for Oxygen-Iodine Laser Applications

The absolute density of singlet oxygen has been quantitatively determined using off-axis integrated cavity output spectroscopy to measure the Q(2)–Q(18) lines of the (0,0) band of the b 1 Σ g + ← a 1 Δ g Noxon system near 1910 nm. Using derived values for the absorption cross-sections and a fitted rotational temperature of 295 K, a singlet oxygen density of 3 × 1015 molecules cm−3 (5% conversion efficiency) was obtained in the afterglow of a 13.56 MHz RF discharge. The observed line spectrum for the Q(12) transition has a signal-to-noise ratio of 120:1 signifying that singlet oxygen densities as low as 2.5 × 1013 molecules cm−3 are detectable.