Doppler broadening thermometry based on cavity ring-down spectroscopy

Cheng, Chuanfu; Wang, J.; Sun, Yuxi; Tan, Yan; Peng, Kang; Hu, S.-M.

doi:10.1088/0026-1394/52/5/s385

Cited by 22 publications

(14 citation statements)

References 44 publications

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“…Similar biases may be encountered for metrological spectroscopic measurements of line intensities or line shapes (e.g. Doppler-broadening thermometry [34,35]).…”

Section: Molecular Absorption Of Infrared Radiation Is Generally Due mentioning

confidence: 66%

Observation of electric-quadrupole infrared transitions in water vapor

Campargue

Kassi

Yachmenev

et al. 2020

Phys. Rev. Research

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“…Similar biases may be encountered for metrological spectroscopic measurements of line intensities or line shapes (e.g. Doppler-broadening thermometry [34,35]).…”

Section: Molecular Absorption Of Infrared Radiation Is Generally Due mentioning

confidence: 66%

Observation of electric-quadrupole infrared transitions in water vapor

Campargue

Kassi

Yachmenev

et al. 2020

Phys. Rev. Research

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“…[1][2][3][4] ), Doppler thermometry (e.g. [5][6][7], amount of gas metrology (e.g. [8][9][10] ) (see also Ref.…”

Section: Introductionmentioning

confidence: 99%

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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“…This is highly promising to bring future DBT experiments to the 1-ppm level over practicable times. In this respect, the 6-ppm value over a "few hours" declared by Cheng et al on acetylene and by CRDS [13] is a further independent indication in favor of a CRDS approach. Concerning systematic uncertainties, negligible contributions come from the natural linewidth, which is below 1 Hz level, and from the pressure leakage, due to a minimal impact on the Gaussian part of the profile.…”

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confidence: 86%

“…A way to overcome these difficulties, while preserving the advantage of a near-infrared spectral range where the linearity of detectors is well assessed [11], is to resort to a highly sensitive detection technique, such as cavity-ring-down spectroscopy (CRDS), enabling the investigation of few-Pascal Doppler regimes and the use of simplified line-shape models. This approach has been recently pursued by Hu et al, by recording acetylene spectra at 787 nm at 1.5 Pa [13]. Nevertheless, their thermometer showed a large systematical deviation (800 ppm) as attributed to weak lines overlapped with the selected transition.…”

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confidence: 99%

Cavity-ring-down Doppler-broadening primary thermometry

et al. 2018

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A step forward in Doppler-broadening thermometry is demonstrated using a comb-assisted cavity-ring-down spectroscopic approach applied to an isolated near-infrared line of carbon dioxide at thermodynamic equilibrium. Specifically, the line-shape of the P e (12) line of the (30012) ← (00001) band of CO 2 at 1.578 µm is accurately measured and its Doppler width extracted from a refined multispectrum fitting procedure accounting for the speed dependence of the relaxation rates, which were found to play a role even at the very low pressures explored, from 1 to 7 Pa. The thermodynamic gas temperature is retrieved with relative uncertainties of 8 × 10 −6 (type A) and 11 × 10 −6 (type B), which ranks the system at the first place among optical methods. Thanks to a measurement time of only ≈5 h, the technique represents a promising pathway toward the optical determination of the thermodynamic temperature with a global uncertainty at the 10 −6 level.DOI: 10.1103/PhysRevA.97.012512The forthcoming redefinition of the unit kelvin [1], in 2018, in terms of a fixed value of the Boltzmann constant, prompts the interest for primary thermometers that are capable to operate over a relatively large part of the temperature scale with very high accuracy. Among primary methods, important advancements [2] have been obtained over the past decade on dielectric constant gas thermometry and Johnson noise thermometry [3,4]. After a first successful experiment of Doppler-broadening thermometry (DBT) [5], followed by significant improvements [6,7], the international community of fundamental metrology recognized the importance of an optical method that links the thermodynamic temperature to an optical frequency, as an independent confirmation of other primary approaches.DBT consists of retrieving the Doppler width ν D from the highly accurate observation of the shape of a given atomic or molecular line, in a laser-based absorption-spectroscopy experiment under a linear regime of radiation-matter interaction [8]. Once ν D is measured, if the central frequency (ν 0 ) and the atomic or molecular mass (M) are known, the inversion of the well-known equationallows one to determine the thermal energy and, consequently, either the gas temperature (T ) or the Boltzmann constant (k B ). So far, the most accurate implementation of DBT has been performed on a rovibrational transition of a water isotopologue at 1.39 µm. Using a dual-laser spectrometer and adopting a very sophisticated spectral analysis procedure, the Boltzmann constant could be determined with a combined uncertainty of 24 parts per million (ppm) [6,9,10].The history of DBT [11] shows that the major hurdle for a low-uncertainty determination of the Doppler width and hence of the thermal energy is the choice of the line-shape model adopted for the spectral analysis. Since a fully ab initio lineshape calculation is prohibitively complex for self-colliding molecules, a model suitable for being implemented into a fitting routine requires approximations and simplifications. At the same time, th...

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Doppler broadening thermometry based on cavity ring-down spectroscopy

Cited by 22 publications

References 44 publications

Observation of electric-quadrupole infrared transitions in water vapor

Observation of electric-quadrupole infrared transitions in water vapor

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

Cavity-ring-down Doppler-broadening primary thermometry

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