A variable-temperature cavity ring-down spectrometer with application to line shape analysis of CO2 spectra in the 1600 nm region

Ghysels, Mélanie; Liu, Qingnan; Fleisher, Adam J.; Hodges, Joseph

doi:10.1007/s00340-017-6686-y

Cited by 29 publications

(60 citation statements)

References 56 publications

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“…3 and 4b show that, within the quadratic speed dependence model for the line width, the temperature dependences of and are different. This is in opposition with the often-used approximation in which the temperature dependences of and are assumed to be the same [56][57][58][59] . The mean values of our rCMDS-predicted and are 0.73 and 0.52, respectively, leading to a difference of about 30 %.…”

Section: The Speed Dependence Of the Line Width And Its Temperature Dmentioning

confidence: 93%

“…5, we compare the rCMDS-predicted values for the ratio 2/0 and the corresponding ones obtained from measured spectra by Wilzewski et al 40 for T = 296 K. The values of Refs. [15,59] and [57,58] [57,58] show large differences with the others which may be due to the line shape used to fit the measured spectra. In fact, in Refs.…”

Section: The Speed Dependence Of the Line Width And Its Temperature Dmentioning

confidence: 99%

“…[57,58], the quadratic speed dependent Voigt profile (qSDV) was used while Refs. [15,40,59] and the present study used the qSDHC model. In order to check this, we used the qSDV profile to fit the rCMDS-calculated spectra.…”

Section: The Speed Dependence Of the Line Width And Its Temperature Dmentioning

confidence: 99%

“…Discussing all the possible sources of difference is beyond the scope of this paper. 58 (green stars), 59 (magenta squares) and 15 (dark yellow triangles) are also reported for comparison.…”

Section: The Speed Dependence Of the Line Width And Its Temperature Dmentioning

confidence: 99%

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Prediction of line shape parameters and their temperature dependences for CO2–N2 using molecular dynamics simulations

Nguyen

2018

The Journal of Chemical Physics

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We show in this paper that requantized classical molecular dynamics simulations (rCMDSs) are capable of predicting various refined spectral-shape parameters of absorption lines of CO2 broadened by N2 with high precision. Combining CMDSs and a requantization procedure, we computed the auto-correlation function of the CO2 dipole moment responsible for the absorption transition. Its Fourier-Laplace transform directly yields the spectrum. Calculations were made for two temperatures, 200 and 296 K, at 1 atm and for a large range of Doppler widths, from the near-Doppler to the collision-dominant regimes. For each temperature and each line, the spectra calculated for various Doppler widths were simultaneously fit with the Hartmann-Tran (HT) profile. This refined profile, which takes into account the effects of the speed dependent collisional line broadening, the Dicke narrowing, and the collisional line mixing, was recommended as a reference model to be used in high-resolution spectroscopy (instead of the simplified Voigt model). The HT parameters retrieved from the rCMDS-calculated spectra were then directly compared with those deduced from high-precision measurements [J. S. Wilzewski et al., J. Quant. Spectrosc. Radiat. Transfer 206, 296–305 (2018)]. The results show a very good agreement, even for those parameters whose influence on the spectra is very small. Good agreement is also obtained between measured and predicted temperature dependences of these parameters. This demonstrates that rCMDS is an excellent tool, highly competitive with respect to high quality measurements for precise line-shape studies.

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Section: The Speed Dependence Of the Line Width And Its Temperature Dmentioning

confidence: 93%

Section: The Speed Dependence Of the Line Width And Its Temperature Dmentioning

confidence: 99%

Section: The Speed Dependence Of the Line Width And Its Temperature Dmentioning

confidence: 99%

Section: The Speed Dependence Of the Line Width And Its Temperature Dmentioning

confidence: 99%

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Prediction of line shape parameters and their temperature dependences for CO2–N2 using molecular dynamics simulations

Nguyen

2018

The Journal of Chemical Physics

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“…It was obtained assuming that the dependence on the relative speed of the collisional broadening is also quadratic. In this particular case, it was shown [181] that the ratio of the broadening speed-dependence parameter to the pressure-broadening coefficient should be independent of T. This result was experimentally confirmed to within a few percent for variable-temperature measurements of CO 2 line shapes in the 1.6 m region [181]. However, some other experimental studies [103,[182][183][184] have shown that the temperature dependences of the line broadening and of its quadratic speed-dependent component are significantly different.…”

Section: 24b Temperature Dependence Of the Line-shape Parametersmentioning

confidence: 67%