High resolution absorption cross-sections and band oscillator strengths of the Schumann-Runge absorption bands of isotopic oxygen, 18O2, at 79 K

Abstract Cross-sections of 18 O 2 at 79 K have been obtained from photoabsorption measurements at various pressures throughout the wavelength region 177.8–197.8 nm with a 6.65 m photoelectric scanning spectrometer equipped with a 2400 lines mm −1 grating and having an instrumental width (FWHM) of 0.0013 nm. The measured absorption cross-sections of the Schumann-Runge bands (14,0) through (2,0) are, with the exception of the (12,0) band, independent of the instrumental width. The measured cross-sections are presented graphically here and are available at wavenumber intervals of ~0.1 cm −1 as numerical compilations stored on magnetic tape, from the National Space Science Data Center, NASA/ Goddard Space Flight Center, Greenbelt, MD 20771, U.S.A. Band oscillator strengths of those bands have been determined by direct numerical integration of the measured absolute cross-sections and are in excellent agreement with our theoretically calculated values.