Vacuum Ultraviolet (VUV) absorption cross section measurements of the atmospherically important molecules nitric oxide and molecular oxygen will be performed with a recently constructed VUV Fourier transform spectrometer that is unique in achieving the very high resolution necessary for the determination of absolute absorption cross sections of molecular bands possessing distinct rotational structure. In the spectral region 175-205 nm, the penetration of solar radiation into the atmosphere is controlled by the absorption of the Schumann-Runge bands of molecular oxygen and some fraction of the transmitted radiation is available to photodissociate NO in bands below 192 nm. The nitric oxide cross sections will be measured in the wavelength below 192 nm. The molecular oxygen cross section will be measured in the wavelength region 175-180 nm where the lines of the Schumann-Runge bands are sharp. In the stratosphere, photodissociation in the Herzberg continuum in the spectral region 200-240 nm, becomes the principal path for molecular oxygen dissociation. Above 242 nm, the Herzberg I bands, which are directly related to the Herzberg continuum, are very sharp. The absorption cross sections of the Herzberg I bands will be obtained at temperatures of 300K and the band oscillator strengths will be determined by the direct integration of the absolute cross sections.
