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.

The absorption spectrum of O₂ and O₂‐O₂ collision pairs were measured over the wavelength range from 330 to 1140 nm using pressures of O₂ from 1 to 55 atm at 298 K. Absorption cross sections, pressure dependences, band centers, and full widths at half maximum of the observed absorption bands centered at 343.4, 360.5, 380.2, 446.7, 477.3, 532.2, 577.2, 630.0, 688, 762, and 1065.2 nm are reported. The absorption bands centered at 360.5, 380.2, and 477.3 nm were also measured at 196 K and their temperature dependences were characterized.

Two collision-induced absorption features of oxygen have been investigated by means of the laser-based cavity ring-down technique at pressures between 0 and 1000 hPa and at temperatures in the range 184–294 K. Peak cross sections, resonance widths and integrated cross sections, as well as spectral profiles, have been determined for the broad O₂O2–O₂O2 resonances centered at 477 and 577 nm. Results are compared with previous measurements to establish an updated temperature dependence for the cross sections of both resonances, yielding integrated cross sections, that exhibit a minimum near 200 K and that increase in a near-linear fashion in the atmospherically relevant range of 200–300 K. A significant increase in the widths of the resonance profiles upon temperature increase is firmly established. Parameters and temperature-dependent trends for the shape and strengths of the resonances are produced, that can be implemented in cloud retrieval in atmospheric Earth observation.

The collision‐induced absorption spectra have been measured at room temperature and at 87°K for bands in the ¹Δ_g + ¹Δ_g ← ³Σ_g⁻ + ³Σ_g⁻ and ¹Δ_g + ¹Σ_g⁺ ← ³Σ_g⁻ + ³Σ_g⁻ simultaneous electronic systems for oxygen. The binary absorption coefficients were found to increase with decreasing temperature for ¹Δ_g + ¹Δ_g ← ³Σ_g⁻ + ³Σ_g⁻. The band shapes for this system suggest that the Hamiltonian which is responsible for intensity borrowing depends on the angular orientation of the O₂ molecules in the collision pair since ΔK  =  0,± 2,± 4 selection rules are needed to account for the Δν_1 / 2  ∼  200cm⁻¹ bandwidth. The relative intensity of the (1–0) and (0–0) bands indicates that the interaction Hamiltonian is also strongly modulated by the vibrational coordinates of O₂. The frequency shift of this simultaneous transition indicates that the intermolecular distance parameter for ¹Δ_g⋅⋅⋅¹Δ_g is 3% larger than for ³Σ_g⁻⋅⋅⋅³Σ_g⁻. The unusual band shape for the ¹Δ_g + ¹Σ_g⁺ ← ³Σ_g⁻ + ³Σ_g⁻ band is interpreted in terms of an exiton interaction for the ¹Δ_g⋅⋅⋅¹Σ_g^>+ combination. Although bound state (O₂)₂ molecules undoubtedly exist at low temperatures these data provide no unambiguous spectroscopic evidence of their presence.