Quantitative measurements of O 2 b ← X(2,1,0←0) bands by using cavity ring-down spectroscopy

Quantitative measurements of individual rotational line intensities of molecular oxygen are made for the (0←0), (1←0), (2←0) bands of the b ¹Σ _g⁺← X ³Σ _g^- transition using highly sensitive cavity ring-down spectroscopy (CRDS). The absorption profiles of six rotational lines of the three bands of O ₂ are measured under pressures up to 1 atm. Corrections have been made to eliminate the effect of laser bandwidth on the absorption intensity measurements. The gas detection limits in our measurement for the three bands are 0.04, 0.80 and 7.00 Torr, respectively. The line strengths in the three bands of O ₂ have been determined by CRDS and are in good agreement with previous results using a multiple pass absorption cell.