S.A. Tashkun

CDSD-1000, the high-temperature carbon dioxide spectroscopic databank

Abstract We present a high-temperature version, CDSD-1000, of the carbon dioxide spectroscopic databank. The databank contains the line parameters (positions, intensities, air- and self-broadened half-widths and coefficients of temperature dependence of air-broadened half-widths) of the four most abundant isotopic species of the carbon dioxide molecule. The reference temperature is T ref =1000 K and the intensity cutoff is I cut =10 −27 cm −1 / molecule cm −2 . More than 3 million lines covering the 260–8310, 418–2454, 394–4662, and 429– 2846 cm −1 spectral ranges for 12 C 16 O 2 , 13 C 16 O 2 , 12 C 16 O 18 O , and 12 C 16 O 17 O , respectively, are included in CDSD-1000. The databank has been generated within the framework of the method of effective operators and based on the global fittings of spectroscopic parameters (parameters of the effective Hamiltonians and effective dipole moment operators) to observed data collected from the literature. Line-by-line simulations of several low- and medium-resolution high-temperature (T=800– 3000 K ) spectra have been performed in order to validate the databank. Comparisons of CDSD-1000 with other high-temperature databanks HITEMP, HITELOR, and EM2C are also given. CDSD-1000 is able to reproduce observed spectra in a more satisfactory way than the high-resolution databank HITEMP for temperatures higher than 1000 K . The databank is useful for studying high-temperature radiative properties of CO2. CDSD-1000 is freely accessible via the Internet.

Methane line parameters in HITRAN

Abstract Two editions of the methane line parameters (line positions, intensities and broadening coefficients) available from HITRAN in 2000 and 2001 are described. In both versions, the spectral interval covered was the same (from 0.01 to 6184.5 cm −1 ), but the database increased from 48,033 transitions in 2000 to 211,465 lines in 2001 because weaker transitions of 12 CH 4 and new bands of 13 CH 4 and CH3D were included. The newer list became available in 2001 in the “Update” section of HITRAN. The sources of information are described, and the prospects for future improvements are discussed.

GLOBAL FITTING OF 12C16O2 VIBRATIONAL–ROTATIONAL LINE POSITIONS USING THE EFFECTIVE HAMILTONIAN APPROACH

About 13 000 experimental lines of the principal isotopic species of CO2 selected from the literature have been used to derive about 100 parameters of a reduced effective Hamiltonian built up to sixth order in the Amat–Nielsen ordering scheme. This Hamiltonian has been obtained from an effective Hamiltonian describing all vibrational–rotational energy levels in the ground electronic state and containing in explicit form all resonance interaction terms due to the approximate relations between harmonic frequencies ω1≈2ω2andω3≈ω1+ω2. An RMS deviation of 0.001 cm-1 has been achieved in the fitting. In order to test its predictive capabilities, the model has been used to calculate the line positions of six bands: 05511←05501, 1005(1, 2)←1004(1, 2), 1006(1, 2)←1005(1, 2), and 20033←00001, which are compared with experimental lines not included in the data set. The results are discussed and compared with the predictions of the Direct Numerical Diagonalization technique.

Global fit of 12C16O2 vibrational–rotational line intensities using the effective operator approach

More than 5000 observed line intensities belonging to 120 vibrational bands of the 12C16O2 molecule selected from the literature have been used to fit 60 parameters of an effective dipole moment. The eigenfunctions of the effective Hamiltonian published in our recent paper have been used in the fits. The regions of ν2,3ν2,5ν2,7ν2,9ν2,and11ν2 bands have been studied. RMS deviations ranging from 2.9 to 13.3% depending on the frequency regions have been achieved. The quality of the fits and the extrapolation properties of the fitted parameters are discussed. The predictions of both line positions and line intensities for perturbed bands 21113←11102, 21113←11101, 40002←11102, 12212←02201, and 23301←02201 are given. The results are compared with the HITRAN-96 database.

Variational EKE-calculations of rovibrational energies of the ozone molecule from an empirical potential function

Abstract We report rovibrational calculations from an empirical potential energy surface (PES) of the electronic ground state of ozone, using an Exact Kinetic Energy (EKE) operator. The PES was optimised using the EKE Hamiltonian and experimental spectroscopic high-resolution data. The RMS deviation of calculations for all experimental band centres directly observed so far in high-resolution spectra is 0.12 cm −1 . The RMS deviation of calculations of rotational energies up to J ⩽5 is 0.002 cm −1 for the (000) level and 0.015 cm −1 for five lowest vibrational states. Both rotational and vibrational calculations are more accurate than presently available EKE-calculations for O 3 . The PES shows a physically meaningful long-range behaviour at the dissociation limit.

Infrared spectra of the 16O12C17O and 16O12C18O species of carbon dioxide: II. The 1500–3000 cm−1 region

Abstract The effective operator approach is applied to the calculation of the spectra of 16 O 12 C 17 O and 16 O 12 C 18 O in the mid infrared. Using the eigenfunctions of the effective Hamiltonians previously derived for each of these species, parameters of the corresponding effective dipole moment operators have been fitted to more than 400 observed line intensities of cold and hot bands covering the ν3 and 2ν1 spectral regions. New line intensities measurements of 16 O 12 C 18 O have been performed. The new observed line intensities have been also included into the corresponding fit. The fittings have been achieved within the experimental errors. A comparison of calculated line parameters with those provided by the HITRAN and GEISA databases is given.

Line intensities of : the 10 micrometers region revisited

Abstract New line intensity measurements in the 10 μm region of 14 N 2 16 O have been performed using FTS in Paris and Reims. About 150 lines in hot bands, including those of the forbidden 0330–0110 band, have been measured for the first time. The new observations together with those available in this region have been used in the fit of effective dipole moment parameters. A dimensionless weighted standard deviation of 1.28 and a RMS deviation of 4.2% have been obtained. Some disagreements with previous measurements and with the HITRAN and GEISA databases have been pointed out for the 0001–1000 and 0220–0000 bands.

Room temperature line lists for CO2 symmetric isotopologues with ab initio computed intensities

Remote sensing experiments require high-accuracy, preferably sub-percent, line intensities and in response to this need we present computed room temperature line lists for six symmetric isotopologues of carbon dioxide: 13C16O2, 14C16O2, 12C17O2, 12C18O2, 13C17O2 and 13C18O2, covering the range 0–8000 cm−1. Our calculation scheme is based on variational nuclear motion calculations and on a reliability analysis of the generated line intensities. Rotation–vibration wavefunctions and energy levels are computed using the DVR3D software suite and a high quality semi-empirical potential energy surface (PES), followed by computation of intensities using an ab initio dipole moment surface (DMS). Four line lists are computed for each isotopologue to quantify sensitivity to minor distortions of the PES/DMS. Reliable lines are benchmarked against recent state-of-the-art measurements and against the HITRAN2012 database, supporting the claim that the majority of line intensities for strong bands are predicted with sub-percent accuracy. Accurate line positions are generated using an effective Hamiltonian. We recommend the use of these line lists for future remote sensing studies and their inclusion in databases.

High-resolution spectroscopy of the triple-substituted isotopologue of water molecule D_{\bf 2}^{\bf 18}O: the first triad

The high-resolution Fourier-transform absorption spectrum of the triple-substituted isotopologue of the water molecule, D O is measured in the 1700–9000 cm−1 region. The transitions of the ν1, 2ν2 and ν3 bands are assigned with the help of the high accuracy variational calculations based on an empirical mass-dependent Partridge–Schwenke potential energy surface. The fittings based on an effective Hamiltonian model are also utilized to confirm the assignments. A set of 816 precise ro-vibrational energy levels for the first triad of interacting vibrational states: (0 0 1), (1 0 0) and (0 2 0) is retrieved. With the upper state combination differences, the ground state energy levels are extended to J max = 23 and . These levels can be used to check the quality of the recently available high accuracy ab initio potential energy surface of the water molecule.

Integration of CO2 spectral line parameters from the CDSD databanks into the virtual atomic and molecular data center (VAMDC)

The spectroscopic banks CDSD-296, CDSD-1000, and CDSD-4000 are presented in the context of integration into the Virtual Atomic and Molecular Data Centre (VAMDC) in order to extend the range of their users. A brief review of the VAMDC system is given concerning the purpose of this project, its infrastructure, and the data representation format. The relational structure of CDSD databases, adapted to VAMDC needs, is presented. Some of the technical problems connected with the huge volumes of stored information are considered.