Réginald Colin

Fourier transform measurement of NO2 absorption cross-section in the visible range at room temperature

New laboratory measurements of NO2 absorption cross-section were performed using a Fourier transform spectrometer at 2 and 16 cm-1 (0.03 and 0.26 nm at 400 nm) in the visible range (380–830 nm) and at room temperature. The use of a Fourier transform spectrometer leads to a very accurate wavenumber scale (0.005 cm-1, 8×10-5 nm at 400 nm). The uncertainty on the new measurements is better than 4%. Absolute and differential cross-sections are compared with published data, giving an agreement ranging from 2 to 5% for the absolute values. The discrepancies in the differential cross-sections can however reach 18%. The influence of the cross-sections on the ground-based measurement of the stratospheric NO2 total amount is also investigated.

Absorption Cross-section of the Collision-Induced Bands of Oxygen from the UV to the NIR

Collision-induced absorption (CIA) cross-sections of oxygen have been measured in the UV, Visible and near-IR regions from spectra recorded by Fourier Transform Spectroscopy at different pressures and room temperature. An extensive cross-sections dataset from 42000 to 7500 cm−1 (238–1330 nm) is presented. The separation procedure of the discrete and diffuse absorption features is described. Pressure and foreign gas effects are discussed, and a comparison with literature data is shown. A preliminary test on the influence of the choice of the dataset on atmospheric retrievals of O2, O3, BrO, and OClO is performed.