J.-M. Flaud

The HITRAN database - 1986 edition

A description and summary of the latest edition of the AFGL HITRAN molecular absorption parameters database are presented. This new database combines the information for the seven principal atmospheric absorbers and twenty-one additional molecular species previously contained on the AFGL atmospheric absorption line parameter compilation and on the trace gas compilation. In addition to updating the parameters on earlier editions of the compilation, new parameters have been added to this edition such as the self-broadened halfwidth, the temperature dependence of the air-broadened halfwidth, and the transition probability. The database contains 348043 entries between 0 and 17,900 cm(-1). A FORTRAN program is now furnished to allow rapid access to the molecular transitions and for the creation of customized output. A separate file of molecular cross sections of eleven heavy molecular species, applicable for qualitative simulation of transmission and emission in the atmosphere, has also been provided.

AFGL atmospheric absorption line parameters compilation - 1982 edition

The latest edition of the AFGL atmospheric absorption line parameters compilation for the seven most active infrared terrestrial absorbers is described. Major modifications to the atlas for this edition include updating of water-vapor parameters from 0 to 4300 cm(-1), improvements to line positions for carbon dioxide, substantial modifications to the ozone bands in the middle to far infrared, and improvements to the 7- and 2.3-microm bands of methane. The atlas now contains approximately 181,000 rotation and vibration-rotation transitions between 0 and 17,900 cm(-1). The sources of the absorption parameters are summarized.

The far infrared spectrum of H2O2. First observation of the staggering of the levels and determination of the cis barrier

High resolution spectra of H2O2, recorded by means of Fourier transform spectroscopy between 30 and 460 cm−1, have been analyzed leading to the determination of the rotational levels of the torsional states (n,τ) for n=0,1,2,3. In order to reproduce these energy levels, Watson type Hamiltonians have been used and it has been possible to observe a staggering of the levels with n=2 and 3 caused by the cis barrier. The torsional band centers have then been fitted using a torsional Hamiltonian of the form {Bγγ,J2γ} +V(γ) with the potential function V(γ) written as V(γ)=V1 cos 2γ+V2 cos 4γ+V3 cos 6γ+V4 cos 8γ where the torsional coordinate 2γ is the dihedral angle defining the relative position of the two O–H bonds. The potential constants in cm−1 are V1=1036.97±23.1 cm−1, V2=657.53±5.2 cm−1, V3=50.89±3.3 cm−1, V4=2.524±0.83 cm−1 which correspond to barrier heights Vtrans =387.07±0.20 cm−1, Vcis =2562.8±60 cm−1, and to a potential minimum located at 2γ=111.9°±0.4° from the cis configuration. It is also shown t...

The ν1 and ν3 bands of 16O3: Line positions and intensities

Abstract Using 0.005 cm −1 resolution Fourier transform spectra of samples of ozone, the ν 1 and ν 3 bands of 16 O 3 have been reanalyzed to obtain accurate line positions and an extended set of upper state rotational levels ( J up to 69, K a up to 20). Combined with the available microwave data, these upper state rotational levels were satisfactorily fitted using a Hamiltonian which takes explicitly into account the strong Coriolis interaction affecting the rotational levels of these two interacting states. In addition, 350 relative line intensities were measured from which the rotational expansions of the transition moment operators for the ν 1 and ν 3 states have been deduced. Finally, a complete listing of line positions, intensities, and lower state energies of the ν 1 and ν 3 bands of 16 O 3 has been generated.

The interacting states (030), (110), and (011) of H216O

Abstract A fit of 382 rotational levels of the three vibrational states (030), (110), and (011) of H 2 16 O has been performed using 51 effective constants. The Fermi-type interaction between (030) and (110) and the Coriolis-type interaction between (110) and (011) as well as between (030) and (011) are taken into account. The part of the Hamiltonian which is diagonal in the vibrational quantum numbers is a Watson-type Hamiltonian. Considering the wide spread of J and K a values, the general agreement between experimental and calculated levels is satisfactory. A comparison with the results relative to the states (020), (100), and (001) is given.

Torsion-vibration interaction in H2O2: First high-resolution observation of ν3

Abstract High-resolution Fourier transform spectra recorded between 450 and 1050 cm −1 have been used to obtain an extensive analysis of several vibration-torsion-rotation bands of H 2 O 2 leading to a precise and extended set of torsion-rotation levels in both the ground and the ν 3 vibrational states of this molecule. In particular, the first observation of the ( n , τ ) = (0, 1) and (0, 3) torsional states of the v 3 = 1 vibrational state is reported. The centers of these two torsional bands are 865.939 and 877.934 cm −1 , respectively. In addition to the observation of ν 3 , new results concerning the ( n , τ) torsional states of the ground state up to n = 3 are presented. All the observed levels have been reproduced with the aid of a Hamiltonian which takes into account the torsion-rotation interactions within a given vibrational state, the staggering due to the cis -barrier, and the strong Coriolis-type interaction which couples the levels of the ground state with those of the v 3 = 1 state. Indeed it is impossible to treat the ground state levels without this interaction, which has been considered here for the first time.

Line positions and intensities for the ν1 + ν2 and ν2 + ν3 bands of H218O

Abstract The intensities of about 90 lines of the ν 1 + ν 2 and ν 2 + ν 3 bands of H 2 18 O have been measured using a Fourier transform spectrum of natural water vapor. The constants involved in the rotational expansion of the transformed transition moment operators corresponding to these bands have been determined through a fit of these line intensities. The constants obtained are used to compute the whole spectrum of the ν 1 + ν 2 and ν 2 + ν 3 bands of H 2 18 O providing reliable line positions and intensities. For lines involving perturbed levels a comparison is given with the results obtained for H 2 16 O and it is shown that the results for one isotopic species cannot be transferred directly to another one.

The far infrared spectrum of 14N16O2

High resolution Fourier transform spectra in the 8–200 cm-1 spectral region have been used to analyse the pure rotation spectrum of nitrogen dioxide. In this way, the spin rotation levels of the (000) state were accurately measured for Ka up to 14 and N up to 54. Using a hamiltonian which takes the spin-rotation and the hyperfine operators explicitly into account, it has been possible to derive a complete set of molecular parameters (rotational, spin-rotation and hyperfine constants) for the (000) state of 14N16O2 from these experimental data and from the available microwave measurements. Numerous perturbations due to the hyperfine Fermi contact operator were analysed as well as a local resonance [42 0 42, J = 41·5] ↔ [41 2 40, J = 41·5] due to the electron spin-rotation interaction. Finally, a synthetic spectrum of the (000) ← (000) band of 14N16O2 including all hyperfine transitions has been computed, covering the 0–235 cm-1 spectral region.

Measurements and calculations of self-broadening coefficients of lines belonging to the v2 band of H216O

The self-broadening coefficients of 150 lines belonging to the v2 band of H216O between 1770 and 2250 cm-1 have been measured using Fourier transform spectra (resolution ≈ 0.005 cm-1). The four different methods which have been used to deduce the self-broadening coefficients from experiment are described in detail. The estimated average uncertainty is about 15% and varies from 7 to 30%, depending on the method used and on the line involved. Two theoretical calculations, one based on the Anderson-Tsao-Curnutte method and the other on the recent method proposed by Davies, have been performed, retaining only the dipole-dipole interaction. For some lines of the v2 band and for some pure rotation lines, calculations based on other formalisms have also been performed. For all of these calculations, we have used accurate spectroscopic data: precise energy levels, realistic wavefunctions, and a complete dipole-moment operator expansion in order to compute the transition probabilities. As compared to the previously calculated values of the pioneering work of Benedict and Kaplan, where the Anderson-Tsao-Curnutte method was used, our calculations show improvements by about 14% in the agreement between measured and calculated self-broadening coefficients.

Line parameters for 16O3 bands in the 7-μm region

Abstract Lines of the very weak 2 ν 2 and ν 1 + ν 3 − ν 2 bands of 16 O 3 have been identified in the region 1370 to 1440 cm −1 of 0.01 cm −1 resolution solar occulatation spectra of the stratosphere. The spectral data were acquired from orbit by the atmospheric trace molecule spectroscopy (ATMOS) Fourier transform spectrometer during the Spacelab 3 shuttle mission. Initial assignments for the lines were obtained by using positions calculated from accurate molecular constants derived in recent high-resolution laboratory studies. From these results and spectral simulations of the interfering atmospheric absorptions, 59 16 O 3 lines in the atmospheric spectra were selected for intensity measurements using the equivalent width technique. Precise transition moment constants for both bands were then deduced from the measured intensities and used with the molecular constants to generate a complete listing of line positions, intensities, and lower state energies useful for atmospheric applications. The integrated band intensities in units of cm −1 /molecule cm −2 at 296 K are 5.43 × 10 −22 for the 2 ν 2 band and 1.01 × 10 −21 for the ν 1 + ν 3 − ν 2 band.