Alain Jenouvrier

Measurements of the NO2 absorption cross-section from 42 000 cm−1 to 10 000 cm−1 (238–1000 nm) at 220 K and 294 K

Abstract The NO2 absorption cross-section has been measured from 42 000 to 10 000 cm−1 (238–1000 nm) with a Fourier transform spectrometer (at the resolution of 2 cm−1, 0.01 nm at 240 nm to 0.2 nm at 1000 nm) and a 5 m temperature controlled multiple reflection cell. The uncertainty on the cross-section is estimated to be less than 3% below 40 000 cm−1 (λ > 250 nm) at 294 K, 3% below 30 000 cm−1 (λ > 333 nm) at 220 K, but reaches 10% for higher wavenumbers. Temperature and pressure effects have been observed. Comparison with data from the literature generally shows a good agreement for wavenumbers between 37 500 and 20 000 cm−1 (267–500 nm). Outside these limits, the difference can reach several percent.

The near infrared, visible, and near ultraviolet overtone spectrum of water

New long path length, high resolution, Fourier transform spectrometer measurements for water are presented. These spectra cover the near infrared, visible, and near ultraviolet regions and contain water transitions belonging to all polyads from 3 nu to 8 nu. Transitions in the range 13 100-21 400 cm(-1) are analyzed using line lists computed using variational first-principles calculations. 2286 new transitions are assigned to (H2O)-O-16. These result in the observation of transitions in 15 new overtone and combination bands of water. Energy levels for these and other newly observed levels are presented. It is suggested that local mode rather than normal mode vibrational assignments are more appropriate for the vibrational states of water in polyads 4 nu and above

Absorption cross-sections of atmospheric constituents: NO2, O2, and H2O

Absorption spectroscopy, which is widely used for concentration measurements of tropospheric and stratospheric compounds, requires precise values of the absorption cross-sections of the measured species. NO2, O2 and its collision-induced absorption spectrum, and H2O absorption cross-sections have been measured at temperature and pressure conditions prevailing in the Earth’s atmosphere. Corrections to the generally accepted analysis procedures used to resolve the convolution problem are also proposed.

The NO2 absorption spectrum. I: Absorption cross-sections at ambient temperature in the 300–500 nm region

New laboratory measurements of NO2 absorption cross-sections have been performed between 300 and 500 nm at ambient temperature with improved experimental conditions: low gas pressures, long absorption paths, suitable absorbance values, narrow spectral bandwidths. The data, stored at 0.01 nm intervals, have been compared to those of the more recent studies and some reasons of disagreement are discussed.In the photolysis region below 400 nm, our absorption cross-sections are larger than those previously published, suggesting that the photodissociation coefficient calculated from the current data sets is underestimated. In the structured region of the spectrum above 400 nm, improvement of the resolution gives more precise values useful for optical measurements in atmosphere.

The NO2 absorption spectrum. II. Absorption cross-sections at low temperatures in the 400–500 nm region

With improved experimental conditions already used for measurements at ambient temperature (Mérienneet al., 1994), new values have been found for the absorption cross-sections of NO2 at 240 and 220 K in the 400–500 nm spectral region. Using a better resolution than in previous studies we show that the temperature effect is not negligible and should be taken into account for the optical measurements of atmospheric NO2 amounts by differential absorption methods.

Water vapor line broadening and shifting by air in the 26,000– region

Abstract Considering the unique role that water in its vapor phase plays in atmospheric physical and chemical processes, there is a need for accurate spectroscopic parameters for this molecule. Long-pathlength Fourier transform spectra of water vapor with synthetic air as the perturbing gas were recorded and analyzed in the 26,000– 13,000 cm −1 spectral region. New measurements of air-broadening and air-shifting parameters with associated uncertainties are presented for about 5000 lines. These data complement our existing database, providing a homogeneous and extensive dataset extending from 26,000 to 9250 cm −1 . Comparisons with the two most frequently used HITRAN and ESA databases as well as with other literature data available are made. Agreements and discrepancies are underlined and briefly discussed.

The near ultraviolet rotation-vibration spectrum of water

A new ab initio linelist of water vibration-rotation transitions extending up to 26 000 cm−1 is presented. This linelist is used to analyze the near-ultraviolet portion of the long pathlength water absorption spectrum of Carleer et al. [J. Chem. Phys. 111, 2444 (1999)]. A total of 299 of the 568 observed transitions between 21 400 and 25 232 cm−1 are assigned. These transitions belong to eight excited vibrational states: (4,2)−1, (7,0)+0, (7,0)−0, (6,0)+2, (6,0)−2, (7,0)−1, (8,0)−0, and (8,0)−0, in local mode notation. Only three of these states have been observed previously. Observed and calculated energy levels are presented for these vibrational states and the band origins are determined.

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.

Fourier Transform Spectroscopy of the O2 Herzberg Bands

The absorption spectra of the O2 Herzberg band systems ( A S u –X S g , c S u –X S g , and A9 D u–X S g ) lying in the wavelength region 240–300 nm were reinvestigated. The coupling of a long absorption cell and a high-resolution Fourier transform spectrometer has allowed the observation of numerous weak lines which were not reported previously. From the rotational analysis of the line positions, determined with an accuracy of 0.005 cm, the molecular constants of the A S u , v 5 0–12, c S u , v 5 2–19, and A9 D u, v 5 2–12 levels are improved significantly. The interaction between the A and c states is described quantitatively. A new interpretation of the perturbations observed in the energy region close to the dissociation limit is given which involves a weakly bound P u state as the most probable perturbing state.

Fourier Transform Spectroscopy of the O2 Herzberg Bands: I. Rotational Analysis

The absorption spectra of the O2 Herzberg band systems ( A S u –X S g , c S u –X S g , and A9 D u–X S g ) lying in the wavelength region 240–300 nm were reinvestigated. The coupling of a long absorption cell and a high-resolution Fourier transform spectrometer has allowed the observation of numerous weak lines which were not reported previously. From the rotational analysis of the line positions, determined with an accuracy of 0.005 cm, the molecular constants of the A S u , v 5 0–12, c S u , v 5 2–19, and A9 D u, v 5 2–12 levels are improved significantly. The interaction between the A and c states is described quantitatively. A new interpretation of the perturbations observed in the energy region close to the dissociation limit is given which involves a weakly bound P u state as the most probable perturbing state.