Visible absorption cross sections and integrated absorption intensities of molecular oxygen (O2 and O4)

Absorption spectra of gas‐phase molecular oxygen and zero air at temperatures of 223 and 283 K have been measured in the laboratory using a coolable multipass‐optics gas cell and Fourier transform spectroscopy in the wavelength range 455 to 830 nm (12,000–22,000 cm−1). Net absorption cross sections of the O2A−, B−, and γ‐bands at <0.002 nm spectral resolution, and pressures of 100 and 1000 hPa zero air have been determined. Binary absorption cross sections of the collision‐induced O4 bands at <0.18 nm spectral resolution and a pressure of 1000 hPa pure oxygen have been determined, with corrections for the O2 γ‐band absorption. Calculated integrated absorption intensities and, for the O2A− and B−bands, “effective” Einstein A‐coefficients are compared with previous literature values.