Spectrally resolved laboratory measurements of oxygen-oxygen collision induced absorption in the 308 – 495 nm range, including the 315, 328, and 421 nm bands | CU Experts

; <p>Oxygen-oxygen collision induced absorption accounts for significant absorption of solar radiation in the atmosphere. It needs to be considered in the interpretation of spectra in absorption spectroscopy. If not represented correctly, it interferes in the retrieval of other trace gases. Quantitative measurements of oxygen-oxygen collision induced absorption, combined with the oxygen concentration vertical profile, allow to constrain radiative transfer processes in the atmosphere. No spectrally resolved cross section data of the bands below 335 nm wavelength and at 420 nm have been available. This study presents spectrally resolved gas-phase laboratory measurements of the oxygen-oxygen collision induced absorption in the ultraviolet and blue spectral range (308 &#8211; 495 nm), including the 315, 328, and 421 nm bands, acquired with Cavity Enhanced Absorption Spectroscopy under atmospherically relevant conditions. While the newly acquired data generally agree with existing data on the strong bands, significant differences consist in a higher signal to noise ratio, a non-zero baseline between bands, and a different band shape of the 344 nm band. This presentation discusses the laboratory setup and analysis scheme used to determine the cross section, and first applications of the cross section to atmospheric data sets.</p>;

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