Recent advances in collisional effects on spectra of molecular gases and their practical consequences

Hartmann, Jean‐Michel; Tran, H.; Armante, R.; Boulet, C.; Campargue, A.; Forget, F.; Gianfrani, L.; Gordon, Iouli E.; Guerlet, Sandrine; Gustafsson, Magnus; Hodges, Joseph T.; Kassi, S.; Lisak, D.; Thibault, Franck; Toon, G. C.

doi:10.1016/j.jqsrt.2018.03.016

Cited by 95 publications

(43 citation statements)

References 689 publications

(880 reference statements)

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“…line position, line intensity and line profile) needed for the forward calculations. It is now well known that one has to take into account refined collisional effects on the spectral profile in order to accurately model the measured lines and to achieve the per mill precision requirement of applications (see [7] and references therein). These effects include the collisions-induced line mixing, the molecular speed dependences of the collisional line broadening and shifting, the collisions-induced velocity changes.…”

Section: Introductionmentioning

confidence: 99%

Line-shape parameters and their temperature dependences predicted from molecular dynamics simulations for O2- and air-broadened CO2 lines

Nguyễn

Ngo

2020

Journal of Quantitative Spectroscopy and Radiative Transfer

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Requantized classical molecular dynamics simulations (rCMDS) were performed for CO2 highly diluted in O2 at 200, 250, 296 and 350 K using a site-site intermolecular potential. The simulations were made for 0.5 atm of O2 pressure and for a large range of Doppler widths, covering near-Doppler regime to collisional-dominant regime. The Fourier-Laplace transform of the auto-correlation functions of the dipole moment, calculated by rCMDS, leads to the associated spectra of CO2 broadened by O2. Different effects of collisions between CO2 and O2 molecules are included in the simulated spectra. In order to determine the profile parameters of O2-broadened CO2 lines, the rCMDS-calculated spectra were fitted with the speed-dependent Nelkin-Ghatak profile associated with the first-order line mixing. The collisional line broadening coefficient, its speed dependence component, the Dicke narrowing and the firstorder line-mixing parameters were retrieved for lines with up to 50 and for all considered temperatures. The temperature dependences of these line-shape parameters were then deduced using the usual single power law. From results obtained in this work and those obtained for CO2 in N2 [Nguyen et al, J Chem Phys, 149, 224301, 2018], the air-broadened line-shape parameters and their temperature dependences for CO2 lines were calculated and compared with literature data showing very good agreement.

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Section: Introductionmentioning

confidence: 99%

Line-shape parameters and their temperature dependences predicted from molecular dynamics simulations for O2- and air-broadened CO2 lines

Nguyễn

Ngo

2020

Journal of Quantitative Spectroscopy and Radiative Transfer

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“…Despite its importance for planetary studies, this continuum has received very little attention, contrary to the self-and N2-(or air-) broadened continua which have been extensively investigated (see reviews in Refs. [2][3][4]) due to their role in the Earth atmosphere. To the best of our knowledge, there are only two works devoted to the continuum of H2O in CO2.…”

Section: Introductionmentioning

confidence: 99%

The CO2–broadened H2O continuum in the 100–1500 cm-1 region: Measurements, predictions and empirical model

Turbet

Hanoufa

Landsheere

et al. 2019

Journal of Quantitative Spectroscopy and Radiative Transfer

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Transmission spectra of H2O+CO2 mixtures have been recorded, at 296, 325 and 366 K, for various pressures and mixture compositions using two experimental setups. Their analysis enables to retrieve values of the "continuum" absorption by the CO2-broadened H2O line wings between 100 and 1500 cm -1 . The results are in good agreement with those, around 1300 cm -1 , of the single previous experimental study available. Comparisons are also made with direct predictions based on line-shape correction factors c calculated, almost thirty years ago, using a quasistatic approach and an input H2O-CO2 intermolecular potential. They show that this model quite nicely predicts, with slightly overestimated values, the continuum over a spectral range where it varies by more than three orders of magnitude. An empirical correction is proposed, based on the experimental data, which should be useful for radiative transfer and climate studies in CO2 rich planetary atmospheres.

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“…It is now widely known that accurate and precise line-shape modeling is necessary to meet the requirements of laboratory measurements and a wide variety of applications (see [1] and references therein, for instance). To this aim, it is recommended that the Hartmann-Tran (HT) [2,3] profile be used for high-resolution spectroscopy [4] to replace the usual Voigt model.…”

Section: Introductionmentioning

confidence: 99%

Prediction of high-order line-shape parameters for air-broadened O2 lines using requantized classical molecular dynamics simulations and comparison with measurements

Tran

Sironneau

Hodges

et al. 2019

Journal of Quantitative Spectroscopy and Radiative Transfer

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et al.. Prediction of high-order line-shape parameters for air-broadened O2 lines using requantized classical molecular dynamics simulations and comparison with measurements. Journal of Quantitative Spectroscopy and Radiative Transfer, Elsevier, 2019, 222-223, pp. AbstractLine-shape models such as the Hartmann-Tran (HT) profile have adjustable high-order parameters that are usually determined by fits to experimental spectra. As an alternative approach, we demonstrate that fitting the HT profile to theoretical spectra provides high-order line-shape parameters for O2 transitions that are consistent with experimentally determined values. To this end, normalized absorption spectra of air-broadened O2 lines were computed without adjustable parameters using requantized classical molecular dynamics simulations (rCMDS). These theoretical calculations were made at a pressure of 203 kPa and for values of the Doppler width that cover near-Doppler-limited to collisional-broadened pressure conditions. Hartmann-Tran (HT) line profiles with adjustable line-shape parameters were then simultaneously fit to the set of rCMDS-calculated spectra in a global multispectrum analysis. The retrieved high-order line-shape parameters (i.e. the speed dependence of the line broadening and the Dicke narrowing coefficient) were subsequently used as fixed HT parameters in the analysis of seven air-broadened O2 lines of the band. The spectra were measured over a fifteen-fold range of total gas pressure at high spectral resolution and signal-to-noise ratio with a frequency-stabilized cavity ring-down spectroscopy system. We show that these predicted parameters enable all the measured lines to be fit to within 1 %, which is much better than best fits of the Voigt line profile to the measured spectra. This approach opens the route for predicting high-order line-shape parameters from first-principles calculations and for their inclusion in spectroscopic databases. Furthermore, the temperature dependences of the broadening coefficient and its speed dependent component for air-broadened O2 lines were also calculated using rCMDS.

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Recent advances in collisional effects on spectra of molecular gases and their practical consequences

Cited by 95 publications

References 689 publications

Line-shape parameters and their temperature dependences predicted from molecular dynamics simulations for O2- and air-broadened CO2 lines

Line-shape parameters and their temperature dependences predicted from molecular dynamics simulations for O2- and air-broadened CO2 lines

The CO2–broadened H2O continuum in the 100–1500 cm-1 region: Measurements, predictions and empirical model

Prediction of high-order line-shape parameters for air-broadened O2 lines using requantized classical molecular dynamics simulations and comparison with measurements

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Recent advances in collisional effects on spectra of molecular gases and their practical consequences

Cited by 95 publications

References 689 publications

Line-shape parameters and their temperature dependences predicted from molecular dynamics simulations for O2- and air-broadened CO2 lines

Line-shape parameters and their temperature dependences predicted from molecular dynamics simulations for O2- and air-broadened CO2 lines

The CO2–broadened H2O continuum in the 100–1500 cm-1 region: Measurements, predictions and empirical model

Prediction of high-order line-shape parameters for air-broadened O2 lines using requantized classical molecular dynamics simulations and comparison with measurements

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The CO2–broadened H2O continuum in the 100–1500 cm-1 region: Measurements, predictions and empirical model