L. Rosenmann

The 1997 spectroscopic GEISA databank

The current version GEISA-97 of the computer-accessible database system GEISA (Gestion et Etude des Informations Spectroscopiques Atmospheriques: Management and Study of Atmospheric Spectroscopic Information) is described. This catalogue contains 1,346,266 entries. These are spectroscopic parameters required to describe adequately the individual spectral lines belonging to 42 molecules (96 isotopic species) and located between 0 and 22,656 cm-1. The featured molecules are of interest in studies of the terrestrial as well as the other planetary atmospheres, especially those of the Giant Planets. GEISA-97 contains also a catalog of absorption cross-sections of molecules such as chlorofluorocarbons which exhibit unresolvable spectra. The modifications and improvements made to the earlier edition (GEISA-92) and the data management software are described. GEISA-97 and the associated management software are accessible from the ARA/LMD (Laboratoire de Meteorologie Dynamique du CNRS, France) web site: http://ara01.polytechnique.fr/registration.

Accurate calculated tabulations of IR and Raman CO 2 line broadening by CO 2 , H 2 O, N 2 , O 2 in the 300–2400-K temperature range

Pressure-broadening coefficients for (12)C(16)O(2) lines have been calculated with a recent model derived from the Robert and Bonamy approach which leads to more accurate results than the previously used Anderson-Tsao- Curnutte model. Systematic calculations of CO(2)-CO(2), CO(2)-H(2)O, CO(2)-N(2), and CO(2)-O(2) broadening coefficients in the 300-2400-K temperature range are presented. The results are suitable for both IR and Raman lines and should be useful for spectra calculations. Tabulations of the broadening coefficients are given together with simple analytical expressions for their rotational quantum number and temperature dependences.

Accurate calculated tabulations of CO line broadening by H 2 O, N 2 , O 2 , and CO 2 in the 200–3000-K temperature range

We present accurate calculations of CO line-broadening coefficients. They have been calculated with a modelwhich has been tested with success on the broadening of CO,-; CO2 and H2O (Refs. 2,9,10) lines. A similar data base for broadening coefficients has already been made for CO2. The following results are presented as in Ref. 11. The broadening coefficients γ‌ m‌ of CO RJ=m-1 lines by H2O, CO2, N2, and O2 have been calculated in the 300-2400K range. The data of Refs. 7,6,4, and 12 have been used for CO-H2O, -CO2, -N2, and -O2, respectively. For a given value of the rotational quantum number m, calculations have only been made for temperatures >Tmin(m), where

Collisional broadening of CO2 IR lines. II. Calculations

The ability of available theoretical models in describing broadening mechanisms is tested for the CO2–O2, CO2–CO2, and CO2–N2 systems. It is shown that the Anderson–Tsao–Curnutte theory is inaccurate since short‐range forces can contribute significantly to broadening. We use the approach of Robert and Bonamy, but the usual expansion of the atom–atom potential to the fourth order around the intermolecular distance appears insufficient at short distances for these particular systems. We propose a better representation of the radial dependence of the atom–atom potential, while keeping the previous analytical expression of the cross section. Satisfactory results are obtained for both the rotational quantum number dependence of room‐temperature CO2–O2, CO2–CO2, and CO2–N2 half‐widths and the evolution of CO2–N2 broadening with temperature. It is shown that the isotropic part of the potential involved in the trajectory calculation must be coherently deduced from the atom–atom interaction potential.

Diode-laser measurements and calculations of CO 1-0 P(4) line broadening in the 294- to 765-K temperature range

Abstract We present first diode-laser measurements of C12O16 1-0 P(4) line broadening by Ar, N2 and H2O at high temperatures, together with the line-intensity value at 300 K. A T-β dependence of line-widths on temperature is deduced from measurements in the 294- to 765-K and 0.2- to 1.2- atm ranges (β = 0.69±0.02, β = 0.69±0.02, β = 0.59±0.05 for Ar, N2 and H2O broadening, respectively). Calculations for CO-Ar and CO-N2 with the model proposed by Robert and Bonamy give very satisfactory results.

Diode-laser measurements and calculations of CO2-line-broadening by H2O from 416 to 805 K and by N2 from 296 to 803 K

Abstract Diode-laser measurements of H 2 O-broadened 12 C 16 O 2 line-widths at high temperature are presented. The T -N dependences of the line-widths are deduced from experiments in the 416–805 K range for the R 42 and R 54 v 3 -band lines broadened by H 2 O. The temperature exponents N (CO 2 -H 2 O) take the values 0.79 ± 0.2 and 0.75 ± 0.2 for the R 42 and R 54 lines, respectively; the corresponding half-widths at 296 K are 0.146 and 0.144 cm -1 -atm -1 . Half-widths and strengths of the R 66 and R 68 v 3 -band lines broadened by N 2 have also been measured in the 296–803 K range. The N (CO 2 -N 2 ) values are 0.66 ± 0.08 and 0.67 ± 0.07 for the R 66 and R 68 lines, respectively, and the corresponding half-widths are 65.2 and 64.2 × 10 -3 cm -1 -atm -1 at 296 K. Calculations for CO 2 line-broadening by H 2 O and N 2 with the model proposed by Robert and Bonamy give satisfactory results.

Collisional broadening of CO2 IR lines. I. Diode laser measurements for CO2–N2 mixtures in the 295–815 K temperature range

We present first diode–laser measurements of N2‐broadened linewidths and strengths of 12C16O2 at high temperature. A T−N dependence of linewidths on temperature is deduced from measurements in the 295–815 K temperature range for the R38, R42, and R54 lines of the ν3 band. The measured line strengths are 21.48±0.49, 12.84±0.28, and 1.82±0.04 cm−2 atm−1 at 300 K for the R38, R42, and R54 lines, respectively. The corresponding half‐widths are 71.02, 70.05, and 67.81×10−3 cm−1 atm−1. The N exponent takes the values 0.73±0.05, 0.72±0.02, and 0.72±0.04.

Measurements and calculations of CO2 absorption at high temperature in the 4.3 and 2.7 μm regions

Abstract Absorption by pure CO2 and CO2-N2 mixtures in the 4.3 and 2.7 μm regions has been measured with a grating spectrometer with spectral resolution of 0.75 and 2cm-1, respectively and pressures between 0.03 and 1 atm, at room temperature and around 750 K. Measurements are compared with line-by-line calculations using the spectroscopic parameters considered for the 1991 edition of the HITRAN database and those calculated by Wattson and Rothman (W-R database) with the Direct Numerical Diagonalization (DND) method. Lorentzian profiles modified by the introduction of a frequency- and temperature-dependent line shape corrective factor χ have been used. At room temperature, calculations with the two databases are consistent and in good agreement with our experiments. At 750 K, calculations with HITRAN underestimate absorption both in line 4.3 and 2.7 μm regions, whereas those with the W-R database are in good agreement with the measurements, with latter slightly underestimating the absorption in the low frequency wing of the 4.3 μm band. This may be due to inaccuracies in the χ factors and the parameters of some hot bands.

Coherent anti‐Stokes Raman spectroscopy study of collisional broadening in the O2–H2O Q branch

The fundamental isotropic Raman Q branch of oxygen perturbed by collisions with water vapor has been studied at pressures up to 1.5 atm and for temperatures between 446 and 990 K. The spectra have been recorded by using coherent anti‐Stokes Raman spectroscopy (CARS) which has been preferred to stimulated Raman spectroscopy (SRS) in order to obtain more signal and higher sensitivity as the mixture has a small percentage of oxygen. The high resolution CARS spectrometer uses a seeded Nd:YAG laser actively stabilized on an external Fabry–Perot interferometer to prevent any frequency drift during the course of the experiment. The line broadening coefficients have been determined for several rotational quantum numbers (up to N=31 at 990 K). The effect of the splitting into triplets at lower pressure and the effect of interferences between neighboring lines at higher pressure have been taken into account. The influence of Dicke narrowing has also been considered and special care has been taken to avoid Stark bro...

Temperature and pressure dependences of absorption in the narrow R66-R68 window of the 12C16O2 v3-band

Abstract Diode-laser measurements of absorption by CO 2 -N 2 mixtures in the trough between the R 66 and R 68 lines of the 12 C 16 O 2 v 3 -band are presented. Experiments have been performed in the 1.0–7.0 atm pressure range at temperatures of 296 and 370 K. The measured absorption is very different from that predicted by the addition of Lorentzian contributions. Theoretical calculations accounting for line-overlapping based on a fitting law are presented. Although the effects of line-overlapping are slightly underestimated, the agreement between experiments and calculations is quite good, for both the pressure and temperature dependences.