Highly accurate intensity factors of pure CO2 lines near 2 μm

Odintsova, T.A.; Fasci, Eugenio; Moretti, Luigi; Żak, Emil J.; Polyansky, Oleg L.; Tennyson, Jonathan; Gianfrani, L.; Castrillo, A.

doi:10.1063/1.4989925

Cited by 27 publications

(20 citation statements)

References 27 publications

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“…There are several methods for determining the line intensity. Data are usually analysed by fitting the peak area of a normalised line profile to the measured spectrum [159,160]. Line intensity determinations from multiple spectroscopic observations can also be analysed and combined by global fits of semi-classical, effective dipole moment surfaces (DMSs) [161].…”

Section: Cavity Ring-down Spectroscopy and Off Axis Integrated-cavitymentioning

confidence: 99%

“…Accurate measurements have also been reported using other techniques including traditional FTIR (see section 4.4), and direct TDLAS (see section 4.3) and cavity-enhanced laser spectroscopy methods. Importantly, these measurements now provide the most stringent tests of ab initio calculations which are contributing to spectroscopic line lists [159,165,171].…”

Section: Cavity Ring-down Spectroscopy and Off Axis Integrated-cavitymentioning

confidence: 99%

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Advances in reference materials and measurement techniques for greenhouse gas atmospheric observations

et al. 2019

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We present the global research landscape which aims to deliver a measurement infrastructure to underpin atmospheric observations of key greenhouse gases governing changes in the Earth's climate. These measurements present a significant challenge to the metrological community, analytical laboratories and major producers of reference materials. The review focuses on the progress made in the Gas Analysis Working Group of the Consultative Committee for Amount of Substance: Metrology in Chemistry and Biology (CCQM-GAWG) in establishing the primary realisation of the amount-of-substance fraction for carbon dioxide, methane and nitrous oxide in an air matrix. It also focuses on the importance of providing traceable measurements of isotopic composition of these components for commutability of reference materials and for isotope ratio measurements for greenhouse gas source attribution. Metrologia 56 (2019) 034006 (29pp) P J Brewer et al 2 of the World Meteorological Organization (WMO) for providing the framework for the development and implementation of integrated greenhouse gas observations, which is vital for understanding the global carbon cycle and the role greenhouse gases play in climate change. The developments in analytical techniques are also discussed which have shaped the direction of the metrology required to meet the evolving and future needs of stakeholders.

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Section: Cavity Ring-down Spectroscopy and Off Axis Integrated-cavitymentioning

confidence: 99%

Section: Cavity Ring-down Spectroscopy and Off Axis Integrated-cavitymentioning

confidence: 99%

Advances in reference materials and measurement techniques for greenhouse gas atmospheric observations

et al. 2019

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“…It was shown that this profile can model measured transitions of various molecular systems to within a few 0.1 % (e.g. [5][6][7][8][9][10][11][12][13]). The international spectroscopic database HITRAN [14] now provides parameters of this profile when available.…”

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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“…It was shown that this profile can model measured spectra of various molecular systems to within a few 0.1 % (e.g. [15][16][17][18][19][20][21][22][23] ). The international spectroscopic database HITRAN 24 now provides parameters for this profile when available.…”

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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Highly accurate intensity factors of pure CO2 lines near 2 μm

Cited by 27 publications

References 27 publications

Advances in reference materials and measurement techniques for greenhouse gas atmospheric observations

Advances in reference materials and measurement techniques for greenhouse gas atmospheric observations

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

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

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