The HITRAN 2004 molecular spectroscopic database

This paper describes the status of the 2004 edition of the HITRAN molecular spectroscopic database. The HITRAN compilation consists of several components that serve as input for radiative transfer calculation codes: individual line parameters for the microwave through visible spectra of molecules in the gas phase; absorption cross-sections for molecules having dense spectral features, i.e., spectra in which the individual lines are unresolvable; individual line parameters and absorption cross-sections for bands in the ultra-violet; refractive indices of aerosols; tables and files of general properties associated with the database; and database management software. The line-by-line portion of the database contains spectroscopic parameters for 39 molecules including many of their isotopologues.The format of the section of the database on individual line parameters of HITRAN has undergone the most extensive enhancement in almost two decades. It now lists the Einstein A-coefficients, statistical weights of the upper and lower levels of the transitions, a better system for the representation of quantum identifications, and enhanced referencing and uncertainty codes. In addition, there is a provision for making corrections to the broadening of line transitions due to line mixing.     

The 2003 edition of the GEISA/IASI spectroscopic database

The content of the current (2003) version, GEISA/IASI-03, of the computer-accessible spectroscopic database, GEISA/IASI, is described. This “system” or database is comprised of three independent spectroscopic archives, which are (a) a database of individual spectral line parameters on 14 molecules, H₂O, CO₂, O₃, N₂O, CO, CH₄, O₂, NO, SO₂, NO₂, HNO₃, OCS, C₂H₂, N₂, and the related 51 isotopomers and isotopologues, representing 702,550 entries, in the spectral range 599-, (b) a database of spectral absorption cross-sections (6,572,329 entries related to six molecules, CFC-11, CFC-12, CFC-14, HCFC-22, N₂O₅, CCl₄), and a catalogue of microphysical and optical properties (mainly, the refractive indices) of atmospheric aerosols. The modifications and improvements, which have been implemented since the earlier editions of this database, in terms of content and management, have been explained in detail. GEISA/IASI has been created with the specific purpose of assessing the capability of measurement by the IASI instrument within the designated goals of ISSWG in the frame of the CNES/EUMETSAT European Polar System preparation.All the archived data can be handled through a user-friendly associated management software, which is posted on the ARA/LMD group web site at http://ara.lmd.polytechnique.fr.     

New High-Resolution Analysis of the nu(3) Band of the (15)N(16)O(2) Isotopomer of Nitrogen Dioxide by Fourier Transform Spectroscopy

New high-resolution Fourier transform absorption spectra of an (15)N(16)O(2) isotopic sample of nitrogen dioxide were recorded at the University of Bremen in the 6.3-μm region. Starting from the results of a previous study [Y. Hamada, J. Mol. Struct. 242, 367-377 (1991)], a new and more extended analysis of the nu(3) band located at 1582.1039 cm(-1) has been performed. The spin-rotation energy levels were satisfactorily reproduced using a theoretical model which takes into account both the Coriolis interactions between the spin-rotation energy levels of the (001) vibrational state with those of the (020) and (100) states and the spin-rotation resonances within each of the NO(2) vibrational states. Precise vibrational energies and rotational, spin-rotation, and coupling constants were obtained in this way for the first triad of (15)N(16)O(2) interacting states {(020), (100), (001)}. Finally, a comprehensive list of line positions and line intensities of the {nu(1), 2nu(2), nu(3)} interacting bands of (15)N(16)O(2) was generated, using for the line intensities the transition moment operators which were obtained previously for the main isotopic species. Copyright 2000 Academic Press.     

The 2ν2 and ν1 bands of HD16O

The 2ν₂ and ν₁ bands of HDO lying in the region 2235–3115 cm^?1 were analyzed using Fourier transform spectra of “pure” D₂O and of H₂OD₂O mixtures. From this analysis, an extended and precise set of rotational levels belonging to the (000), (020), and (100) vibrational states was derived. Using the (000) levels together with the existing microwave data as input in a least-squares fit, it was possible to obtain reliable rotational constants for the ground state of the HDO molecule.     

Diode laser spectra of the ν2 band of 14N16O2: The (010) state of NO2

Diode laser spectra of the ν₂ band of NO₂ are recorded and analyzed. Due to the very high resolution (0.002 cm^?1), the Q branches are completely resolved. Although the whole ν₂ band is not completely covered, the quality of the spectra led to an improved set of rotational and spin-rotation constants. The band center is found to be ν₂ = 749.6541 ± 0.0012 cm^?1.     

Spectrum of water vapor between 8050 and 9370 cm−1

Measurements of the line positions of H₂¹⁶O in the 8050 to 9370 cm^?1 region have been performed at a spectral resolution of 0.07 cm^?1. A grating spectrum of room-temperature water vapor and a Fourier transform spectrum of heated water vapor (T ? 60°C) were used in the interpretation. A careful analysis of the bands ν₁ + 3ν₂, 3ν₂ + ν₃, 2ν₁ + ν₂, ν₁ + ν₂ + ν₃, and ν₂ + 2ν₃ has led to a set of rotational levels belonging to the vibrational states (130), (031), (210), (111), and (012). Many vibrorotational resonances were detected.     

Experimental and theoretical study of line mixing in NH3 spectra. II. Effect of the perturber in infrared parallel bands

In a previous paper [J. Chem. Phys. 116, 7544 (2002) (Paper I)] a model, based on the energy corrected sudden approximation, was proposed for the construction of the line-mixing relaxation matrix. It was successfully tested by comparisons with measured infrared spectra of ammonia-helium mixtures. The present paper extends this preliminary study by considering mixtures of NH3 with H2 and Ar. Measurements have been made at room temperature in the regions of the nu2 and nu1 bands for pressures up to several hundred atmospheres. As in Paper I, the relaxation operator is constructed, within the impact approximation, using the ECS approximation. The data required are dynamical factors (which can be predicted from the NH3-X potential energy surface) and a scaling length (adjusted using line broadening data). Comparisons between measured and calculated absorptions demonstrate the quality of the model which satisfactory corrects for the large deviations with respect to the purely Lorentzian behavior. Line-mixing effects for NH3-Ar and NH3-H2 are qualitatively similar to those observed for NH3-He but quantitative differences exist, particularly when intra- and interbranch couplings are considered. Finally, the proposed model leads to very satisfactory results in the wings of both the purely rotational and nu2 bands of NH3 diluted in H2, opening promising perspectives for the remote sensing study of planetary atmospheres.     

Infrared line collisional parameters of HCl in argon, beyond the impact approximation: measurements and classical path calculations

Measurement of room temperature absorption by HCl-Ar mixtures in the 1-0 and 2-0 bands have been made for pressures between 10 and 50 atm. Fits of these spectra are made for the determination of the width, spectral shift, asymmetry, and intensity of individual lines. The broadening and shifting parameters are in satisfactory agreement with previous determinations but provide the first complete and self-consistent sets covering P(15)-R(14) and P(7)-R(8) in the 1-0 and 2-0 bands, respectively. The asymmetries of the profiles, which have been studied for the first time, are smaller than typically 10(-3) atm(-1) and cannot be determined experimentally. On the other hand, the intensities of the low j lines show a significant linear decrease with increasing Ar pressure. Calculations of all measured quantities are made with a classical path approach and an accurate vibrational-dependent HCl-Ar potential energy surface (PES). Comparisons with experimental values show that widths and shifts are well predicted, confirming the quality of the PES and of the theoretical model, and the calculations confirm that asymmetries are small. The damping factors of the intensities are analyzed by considering three contributions: The first is due to the formation of van der Waals complexes, the second results from the finite duration of collisions, and the last comes from initial correlations. Calculations indicate that the last process has negligible consequences but that the first two processes lead to effects of the same order and explain most of the observed decrease of the intensities, even if some discrepancies persist for the mid R:mmid R:=1 rotational components.     

Microwave and Submillimeter-Wave Measurements of HDCO in the ν4, ν5, and ν6 Bands: Evidence of Vibrational Induced Rotational Axis Switching (“VIRAS”)

The rotational spectrum of HDCO in the 4¹, 5¹, and 6¹ excited vibrational states has been investigated in Lille and Kiel using a sample enriched in deuterium. In Lille, the measurements were performed in the millimeter region (160-600 GHz). The spectra in Kiel were recorded using Fourier transform microwave spectrometers in the regions around 8-18 and 18-26 GHz, employing a rectangular waveguide of length 12 m and a circular waveguide of length 36 m, respectively. These results were combined with the 4¹, 5¹, and 6¹ infrared energy levels which were obtained from a previous analysis of FTS spectra of the ν₄ (CHD bend), ν₅ (CHD rocking), and ν₆ bands (out of plane bend) recorded in the 10-μm region at Giessen (A. Perrin, J.-M. Flaud, M. Smirnov, and M. Lock, J. Mol. Spectrosc.203, 175-187 (2000)). The energy level calculation of the 4¹, 5¹, and 6¹ interacting states accounts for the usual A- and B-type Coriolis resonances in the 5¹⇔6¹ and 4¹⇔6¹ off diagonals blocks. In addition, since the energy levels of the 5¹ and 6¹ states are very strongly resonating, it proved necessary, as in our previous study, to use a {J_x, J_z} nonorthorhombic term in the 5¹ and 6¹v-diagonal blocks of the Hamiltonian matrix in order to reproduce properly the observed microwave transitions and infrared energy levels. Therefore, this work confirms that HDCO is a good example of the vibrational induced rotational axis switching (“VIRAS”) effect.