A strategy to complete databases with parameters of refined line shapes and its test for CO in He, Ar and Kr

Ngo, N.H.; Hartmann, Jean‐Michel

doi:10.1016/j.jqsrt.2017.01.031

Cited by 15 publications

(21 citation statements)

References 29 publications

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“…As demonstrated previously for O2 [18,24] and for other molecular systems [15,17,19,20,30], the non-Voigt effects observed on the rCMDS-calculated spectra are in very good agreement with those of measured spectra (through comparison of their Voigt fits residuals and parameters). However, line broadening coefficients predicted by rCMDS can be significantly different from measured values.…”

Section: Analysis Proceduressupporting

confidence: 85%

“…In [15,16], it was shown that first-principles calculations based on molecular configurations and intermolecular potentials, combined with a limited amount of information obtained from measurements successfully predicts the shapes of CO and H2O ro-vibrational lines. Indeed, these theoretical calculations are based either on classical molecular dynamics simulations (CMDS) [15] or a combination of CMDS and semi-classical methods (see [16] and references therein). It was shown that the non-Voigt effects observed in the measured spectra are well predicted by these first-principles calculations, for various molecular systems (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…[17][18][19][20][21][22]) although the difference between the computed and measured line widths could be several percent. In [15,16], the calculations were thus empirically improved by introducing a measured value of the line width into the computed auto-correlation function of the transition dipole moment, where the line-shape equals the Fourier-Laplace transform of the latter quantity. With this correction procedure, it was shown that the calculations can predict measured spectra of several lines of CO [15] and H2O [16] over a large pressure range to within 1 %, significantly better than the best fits of the measurements with the usual Voigt profile.…”

Section: Introductionmentioning

confidence: 99%

“…In [15,16], the calculations were thus empirically improved by introducing a measured value of the line width into the computed auto-correlation function of the transition dipole moment, where the line-shape equals the Fourier-Laplace transform of the latter quantity. With this correction procedure, it was shown that the calculations can predict measured spectra of several lines of CO [15] and H2O [16] over a large pressure range to within 1 %, significantly better than the best fits of the measurements with the usual Voigt profile. In this work, first-principles CMDS calculations of line-shapes were used to provide theoretical spectra from which high-order line-shape parameters could be retrieved.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Analysis Proceduressupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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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“…21 Once the appropriate model is chosen, rCMDS calculated spectra can also be used to predict the different line shape parameters, especially the high order line shape parameters such as those used to describe the collision-induced velocity changes, the speed dependence of the linewidth, as well as their pressure and temperature dependences, as what was done for CO, for instance. 39 …”

Section: Data Analysis and Resultsmentioning

confidence: 99%

Molecular dynamic simulations of N2-broadened methane line shapes and comparison with experiments

Doménech

Lepère

2017

The Journal of Chemical Physics

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Absorption spectra of methane transitions broadened by nitrogen have been calculated for the first time using classical molecular dynamic simulations. For that, the time evolution of the auto-correlation function of the dipole moment vector, assumed along a C–H axis, was computed using an accurate site-site intermolecular potential for CH4–N2. Quaternion coordinates were used to treat the rotation of the molecules. A requantization procedure was applied to the classical rotation and spectra were then derived as the Fourier-Laplace transform of the auto-correlation function. These computed spectra were compared with experimental ones recorded with a tunable diode laser and a difference-frequency laser spectrometer. Specifically, nine isolated methane lines broadened by nitrogen, belonging to various vibrational bands and having rotational quantum numbers J from 0 to 9, were measured at room temperature and at several pressures from 20 to 945 mbar. Comparisons between measured and calculated spectra were made through their fits using the Voigt profile. The results show that ab initio calculated spectra reproduce with very high fidelity non-Voigt effects on the measurements and that classical molecular dynamic simulations can be used to predict spectral shapes of isolated lines of methane perturbed by nitrogen.

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References

2021

Collisional Effects on Molecular Spectra

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A strategy to complete databases with parameters of refined line shapes and its test for CO in He, Ar and Kr

Cited by 15 publications

References 29 publications

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

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

Molecular dynamic simulations of N2-broadened methane line shapes and comparison with experiments

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