Precise line parameters and transition probability of the atmospheric A band of molecular oxygen O-16(2)

High-resolution Fourier transform absorption spectroscopy was employed to d etermine line parameters and the transition probability of the visible b (1 )Sigma(g)(+) (upsilon = 0) <-- X (3)Sigma(g)(-) (upsilon = 0) band (A band) of molecular oxygen, O-16(2), in order to improve the currently available data for application in atmospheric science. Spectra were recorded at room temperature and 198 K, for pure oxygen pressures between 21 and 1000 hPa, a nd at absorption pathlengths between 32.75 and 128.75 m, The spectrometer r esolution varied from 0.0069 to 0.029 cm(-1) depending on the line widths. Line intensities and self-broadening coefficients were retrieved at both te mperatures using a least-squares line-fitting procedure. Collisional narrow ing of a Voigt line profile, which was found to be of the order of magnitud e of 0.009 cm(-1) atm(-1), had to be included in the fitting procedure in o rder to fit the observed line profiles. Combining the data from all spectra , line intensities with an accuracy of approximately 0.3% and self-broadeni ng coefficients with errors of 2-3% were derived for both temperatures, all owing the determination of their temperature dependence. The line-by-line i ntensity analyses were combined for each spectrum in order to determine the vibronic A band cross-section and the Einstein transition probability with standard errors of less than 0.1%. (C) 1999 Elsevier Science Ltd. All righ ts reserved.