Integrated absorption intensity and Einstein coefficients for the O_2 a~1#DELTA#_g-X~3#SIGMA#_g~- (0,0) transition: A comparison of cavity ringdown and high resolution Fourier transform spectroscopy with a long-path absorption cell

摘要

The two experimental techniques of cavity ringdown spectroscopy and high-resolution, long-path Fourier transform spectroscopy have been used to measure quantitative absorption spectra and determine the integrated absorption intensity (S _(int, B)) for the O_2 a ~1#DELTA#_g - X ~3#SIGMA#_g~- (0, 0) band. Einstein A-factors and radiative lifetimes for the O_2 a ~1#DELTA#_g #upsilon# = 0 state have been derived from the S_(int,B) values. The two methods give values for the integrated absorption intensity that agree to within 2%. The value recommended from the results of this study is S_(int, B) = 3.10 +- 0.10 * 10~(-24) cm molecule~(-1), corresponding to an Einstein-A coefficient of A = 2.19 +- 0.07 * 10~(-4) s ~(-1) and a radiative lifetime of #tau#_(rad) = 76 min. The measurements are in excellent agreement with the recent absorption study of Lafferty et al. [Appl. Opt. 37, 2264 (1998)] and greatly reduce the uncertainty in these parameters, for which accurate values are required for determination of upper stratospheric and mesospheric ozone concentrations.