Herzberg Continuum Cross Section of Oxygen in the Wavelength Region 193. 5-204. 0 nm and Band Oscillator Strengths of the (0,0) and (1,0) Schumann-Runge Bands.

Abstract

Cross sections of oxygen at 300 K have been obtained from photoabsorption measurements at various pressures, from 50 to 760 Torr (1 Torr equals 133. 3 Pa), at wavelength intervals of 0. 0002 nm throughout the region 193. 5-204. 0 nm with a 6. 65-m photoelectric scanning spectrometer equipped with a 2400 line/mm grating and having an instrumental full width at half maximum of 0. 0013 nm. The spectral features contributing to absorption in this region are the discrete lines of some Schumann-Runge bands and underlying dissociation continua consisting of the weak Herzberg continuum of O//2 and a pressure dependent continuum involving two molecules of O//2. Analysis of the pressure dependence of the total continuum cross section in window regions between the discrete lines yields the Herzberg continuum cross section. Band oscillator strengths of certain Schumann-Runge bands have been determined by direct numerical integration of the measured discrete cross section remaining after subtraction of the continua from the total cross section. Improved wavenumber measurements of the Schumann-Runge bands are given.