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Highlights • 5819 line positions and intensities were retrieved from measured spectra in the 5550- 5825 cm−1 region. • More than 2800 new assignments were made in the region. • More than 3445 experimental line positions were modeled to 0.0024 cm−1. Abstract A new study of 12CH 4 line positions and intensities was performed for the Tetradecad regions 5550,000–5695.250, 5718.8–5724.250 and 5792.36–5814.290 cm−1 using long path (202 m, 602 m, 1604 m and 1804 m) spectra of normal samples of CH 4 at different pressures recorded with a Fourier transform spectrometer in Reims, France. Line positions and intensities were retrieved by least squares curve-fitting procedures and analyzed using the effective Hamiltonian and the effective dipole moment expressed in terms of irreducible tensor operators adapted to spherical top molecules. An 80 K spectrum recorded in Jet Propulsion Laboratory (JPL), Pasadena, of enriched 12CH 4 was used for low-J line positions. Another 80 K spectrum of enriched 13CH 4 from JPL was used to discern the isotopic lines. A new measured linelist contains positions and intensities for 5819 features. Quantum assignments were made for more than 3400 transitions, which represent ∼95% of the integrated line intensity observed in this region. All assigned 3445 line positions were fitted with RMS standard deviations of 0.0024 cm−1. The sum of observed intensities between 5550 and 5695 cm−1 fell within 2% of the predicted value from ab initio variational calculations reported in the TheoReTS database (http://theorets.univ-reims.fr ; http://theorets.tsu.ru). [ABSTRACT FROM AUTHOR]

A new study of 12 CH 4 line positions and intensities was performed for part of the Tetradecad region between 5300 and 5550 cm −1 using four long path (202 m, 602 m, 1604 m and 1804 m) spectra of normal samples of CH 4 at different pressures recorded with a Fourier transform spectrometer in Reims, France. Line positions and intensities were retrieved by least square curve-fitting procedures and analyzed using the effective Hamiltonian and the effective dipole moment expressed in terms of irreducible tensor operators adapted to spherical top molecules. An 80 K spectrum from JPL of enriched 12 CH 4 was used for low-J line positions. One other 80 K spectrum from JPL of enriched 13 CH 4 was used to discern the isotopic lines. A new measured linelist contains positions and intensities for 5934 features. Quantum assignments were made for 2847 transitions, which represent ∼90% of the integrated line intensity observed in this region. All assigned line positions and 2227 selected line intensities were fitted with RMS standard deviations of 0.0025 cm −1 and 8.6%, respectively. The sum of observed intensities between 5300 and 5550 cm −1 fell within 2% of the predicted value from ab initio variational calculations. [ABSTRACT FROM AUTHOR]

This paper presents the results of a spectroscopic line shape study of self- and nitrogen-broadened 12 CH 3 D transitions in the ν 3 and ν 5 bands in the Triad region. We combined five pure gas spectra with eighteen spectra of lean mixtures of 12 CH 3 D and nitrogen, all recorded with a Bruker IFS-125 HR Fourier transform spectrometer. The spectra have been analyzed simultaneously using a multispectrum nonlinear least squares fitting technique. N 2 -broadened line parameters for 184 transitions in the ν 3 band and 205 transitions in the ν 5 band were measured. In addition, line positions and line intensities were measured for 168 transitions in the ν 3 band and 214 transitions in the ν 5 band. We have observed 10 instances of weak line mixing corresponding to K ″=3 A1 or A2 transitions. Comparisons were made for the N 2 -broadening coefficients and associated temperature exponents with corresponding values calculated using a semi-classical Robert Bonamy type formalism that involved an inter-molecular potential with terms corresponding to short- and long-range interactions, and exact classical molecular trajectories. The theoretical N 2 -broadened coefficients are overestimated for high J values, but are in good agreement with the experimental values for small and middle range J values. [ABSTRACT FROM AUTHOR]

Abstract: Temperature dependences of pressure-broadened half-width and pressure-induced shift coefficients along with accurate positions and intensities have been determined for transitions in the 2←0 band of 12C16O from analyzing high-resolution and high signal-to-noise spectra recorded with two different Fourier transform spectrometers. A total of 28 spectra, 16 self-broadened and 12 air-broadened, recorded using high-purity (≥99.5% 12C-enriched) CO samples and CO diluted with dry air (research grade) at different temperatures and pressures, were analyzed simultaneously to maximize the accuracy of the retrieved parameters. The sample temperatures ranged from 150 to 298K and the total pressures varied between 5 and 700Torr. A multispectrum nonlinear least squares spectrum fitting technique was used to adjust the rovibrational constants (G, B, D, etc.) and intensity parameters (including Herman–Wallis coefficients), rather than determining individual line positions and intensities. Self- and air-broadened Lorentz half-width coefficients, their temperature dependence exponents, self- and air-pressure-induced shift coefficients, their temperature dependences, self- and air- line mixing coefficients, their temperature dependences and speed dependence have been retrieved from the analysis. Speed-dependent line shapes with line mixing employing off-diagonal relaxation matrix element formalism were needed to minimize the fit residuals. This study presents a precise and complete set of spectral line parameters that consistently reproduce the spectrum of carbon monoxide over terrestrial atmospheric conditions. [Copyright &y& Elsevier]