A. Perrin

The hitran molecular database : editions of 1991 and 1992

Abstract We describe in this paper the modifications, improvements, and enhancements to the HITRAN molecular absorption database that have occurred in the two editions of 1991 and 1992. The current database includes line parameters for 31 species and their isotopomers that are significant for terrestrial atmospheric studies. This line-by-line portion of HITRAN presently contains about 709,000 transitions between 0 and 23,000 cm-1 and contains three molecules not present in earlier versions: COF2, SF6, and H2S. The HITRAN compilation has substantially more information on chlorofluorocarbons and other molecular species that exhibit dense spectra which are not amenable to line-by-line representation. The user access of the database has been advanced, and new media forms are now available for use on personal computers.

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.

The NO Dimer.

Spectra of the symmetric nu1 vibration of the NO dimer have been recorded in gas phase at low temperature, with a high-resolution infrared Fourier transform spectrometer. All the lines were least-squares fitted to a Voigt profile convoluted with the well-known apparatus function of the spectrometer. By means of this method, the frequencies of more than 109 new lines were measured. From the intensities of a set of 33 well-fitted and completely isolated lines, the transition moment was extracted. NO-broadening coefficients of the dimer lines were also measured as well as the predissociation time, which was found to be (2.65 +/- 0.53) ns. Copyright 1999 Academic Press.

The v 3 and v 4 interacting bands of HNO3 line positions and line intensities

Very high resolution Fourier transform spectra of HNO3 recorded in the 1230–1370 cm-1 spectral region have been extensively analysed leading to precise line positions and intensities for the v 3 and v 4 bands of this molecule. Then, using a hamiltonian which takes explicitly into account the Fermi and Coriolis resonances between these two bands, it has been possible to reproduce satisfactorily the majority of the v 3 and v 4 interacting rotational levels. Moreover resonances due to unobserved vibrorotational levels are discussed. Intensities of 218 individual transitions belonging to the v 3 and v 4 bands were measured allowing a precise determination of the constants involved in the expansion of the corresponding transition moment operators. Finally a complete synthetic spectrum of the v 3 and v 4 bands of HNO3 has been computed.

New measurements in the millimeter-wave spectrum of 14N16O2

Abstract One hundred eleven new microwave transitions belonging to the ground state of 14 N 16 O 2 have been observed in the spectral region 180–300 GHz. A discussion of the impact of the earths magnetic field leading to an observed Zeeman effect is presented.

The ν2 band of 14N16O2—Spin-rotation perturbations in the (010) state

Abstract A high-resolution Fourier transform spectrum recorded in the spectral region 570–960 cm −1 has been used to analyze the ν 2 band of 14 N 16 O 2 and the spin-rotation levels of the (010) vibrational state have been obtained for K a up to 11 and N up to 53. Using a Hamiltonian which takes explicitly into account the spin-rotation as well as the hyperfine interactions, it was possible from these data and the available microwave measurements in the (010) state to derive a complete set of molecular parameters (band center and rotational, spin-rotation, and hyperfine constants) for the (010) vibrational state of 14 N 16 O 2 . During the course of the analysis resonance effects were observed and analyzed and, as an example, the local resonance [46 0 46, J = 45.5] ↔ [45 2 44, J = 45.5] due to the electron spin-rotation operator is described in detail. Finally the synthetic spectra of the (010) ← (010) and the (010) ← (000) bands of 14 N 16 O 2 were calculated.

The ν2 bands of 18O3, 18O16O18O, and 16O18O18O: Line positions and intensities

Abstract Using 0.005 cm−1 resolution Fourier transform spectra of an 18O-enriched ozone sample, an extensive analysis of the ν2 bands of the three isotopic species 18O3, 18O16O18O, and 16O18O18O has been performed for the first time. For each isotopic species, the infrared vibration-rotation energies obtained from this analysis, together with the available microwave transitions in the ground state, were reproduced within their experimental uncertainties using a Watson A-type Hamiltonian. The following band centers were obtained: v 2 ( 18 O 3 ) = 661.49248 cm −1 v 2 ( 18 O 16 O 18 O) = 668.08496 cm −1 v 2 ( 16 O 18 O 18 O) = 677.50382 cm −1 . In addition, precise rotational and centrifugal distortion constants were obtained both for the ground state and for the first vibrational state (010) of the three isotopic species. Appropriate expansions of the transformed transition moment operators of the three ν2 bands were used to generate a complete list of line positions, intensities, and lower-state energy levels for the 18O3, 18O16O18O, and 16O18O18O isotopic species.

New analysis of the ν6 band of H2O2: The (n, τ) = (0, 1), (1, 1), (2, 1), (0, 3), and (1, 3) torsional subbands

Abstract The ν 6 band of H 2 O 2 has been recorded at a resolution of 0.002 cm −1 by means of Fourier transform spectroscopy in the spectral region 1190–1330 cm −1 . The ( n , τ ) = (0, 1), (1, 1), (2, 1), (0, 3), and (1, 3) torsional subbands have been extensively analyzed leading to a large and precise set of torsion-rotation energy levels for the v 6 = 1 vibrational state. Numerous resonances have been observed and are discussed. For the ( n , τ ) = (0, 3), (1, 3) rotational levels the resonances are mainly due to the v 2 = 1 vibrational state whereas for the ( n , τ ) = (0, 1), (1, 1), and (2, 1) rotational levels, the v 3 = 1 vibrational state and/or the ground state is also involved. For the ( n , τ ) = (0, 3), and (1, 3) torsional states it has been possible to satisfactorily fit the experimental energies using a Hamiltonian which takes simultaneously into account both the interactions between the torsional states within the v 6 = 1 state and the v -off diagonal ( v 6 = 1 ↔ v 2 = 1) interaction between the levels of the v 6 = 1 and v 2 = 1 vibrational states. As very few data are available concerning the v 3 = 1 vibrational state it has not been possible to perform a similar calculation for the ( n , τ ) = (0, 1), (1, 1), and (2, 1) torsional states and the least-squares fit was performed taking into account only the resonances within the v 6 = 1 state and neglecting the resonances with the other vibrational states. Finally, using the ( n , τ ) = (0, 1), (1, 1), (2, 1), (0, 3), and (1, 3) torsional band centers the cis - and trans -barrier heights of the v 6 = 1 vibrational state have been estimated.

Calculated line positions and intensities for the v1 + v3 and v1 + v2 + v3 - v2 bands of 14NO2

Abstract Using a Hamiltonian which takes explicitly into account the Coriolis resonance between the (v1, v2 v3) and (v1 v2 + 2 v3 − 1) states of NO2, we have fitted the available rotational levels of the interacting states (1 2 0) and (1 0 1) as well as the rotational levels of the interacting states (1 3 0) and (1 1 1). A least squares fit of the intensities of the v1 + v3 band has provided us with the expansion of the transformed transition moment of this band. Then using this transition moment as well as the wavefunctions and the energy levels deduced from the diagonalization of the Hamiltonian matrix, we have generated an improved set of line parameters for the bands absorbing in the 3.4μm region: namely the v1 + v3 band and its associated hot band v1 + v2 + v3 - v2.

Line positions and intensities for the ν2+3ν3 band of 16O3 around 2.7 μm

Abstract The absorption spectrum of ozone has been recorded between 3600 and 3900 cm −1 at 0.01 cm −1 resolution with a Fourier transform spectrometer. The analysis of the spectra has allowed the first high-resolution study of the ν 2 + 3 ν 3 band of the 16 O 3 molecule. The experimental rotational energy levels of the (013) vibrational state have been measured up to J = 40 and K a = 13 allowing an accurate set of rotational constants to be determined with a Hamiltonian taking into account the Coriolis resonances with the unobserved (112) vibrational state. Moreover, 71 line intensities measured with a relative uncertainty of about 8% were least-squares fitted leading to the determination of the main ν 2 + 3 ν 3 transition moment constants. Finally, a complete list of line positions, intensities, and lower state energies was generated for the ν 2 + 3 ν 3 and ν 1 + ν 2 + 2 ν 3 bands of 16 O 3 .