Measurement of the radiative lifetime of O2(a1Δg) using cavity ring down spectroscopy

Cavity ring down spectroscopy has been used to detect the weak a(1)Delta (g) - X(3)Sigma (-)(g) electronic transition in oxygen and to obtain a measurement of the radiative lifetime of the a(1)Delta (g) state. (0,0) band transitions near 1274 nm were scanned using the frequency-doubled output of a tunable OPO system. Pressure-broadened linewidths were measured, and a FWHM-broadening coefficient of 5.5(5) MHz/Torr was obtained. Analysis of the ring down traces provided a measurement of the line strength of an individual rovibronic transition. The Einstein A-coefficient of the a(1)Delta (g) state was calculated using branching ratios determined from the Honl-London factors. The A-coefficient obtained is 2.3(3) x 10(-4) s(-1), corresponding to a radiative lifetime of 4300(500) s ( similar to 72 min). This value is in agreement with those reported by Badger et al. (2.58 x 10(-4) s(-1)) and Spalek et al, (2.24(40) x 10(-4) s(-1)). In addition, a value of 2.77(8) x 10(-45) cm(5)/molecule was obtained for the background collisional absorption coefficient for oxygen at 1274 nm. Published by Elsevier Science Ltd.