Fourier transform spectroscopy of atmospheric gases

NO2 absorption cross-sections have been obtained at 220 K and 294 K at a resolution of 2 cm-2 from a series of spectra recorded with pure NO2 at pressures from 0.007 to 2 torr. The N2O4 absorption cross-section has been obtained at 220 K. The uncertainty in the NO2 cross-sections is estimated to be less than 3 percent for the spectral region below 40000 cm-1 at 294 K, 3 percent below 30000 cm-1 at 220 K. Temperature and pressure effects have been observed. Comparison with literature data show good agreement between 37500 and 20000 cm-1. O2 absorption spectra have been recorded at high and low resolution in the UV. A re-analysis of the three Herzberg band systems has been performed, extending the rotational assignment up to N equals 31 and identifying several new vibrational bands. Determination of the integrated intensities and oscillator strengths of the bands has been performed. These values have been compared with data of the literature. Spectra recorded with increasing pressures of N2 or Ar show that the structure d continuum overlapping the Herzberg bands cannot be explained by O2-O2 absorption, but comes from collision induced absorption. Low resolution spectra have also been recorded in the visible region in order to determine the (O2)2 absorption cross-section.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.