Collisional parameters of H2O lines: Velocity effects on the line-shape

Tran, H.; Bermejo, Dionisio; Doménech, José Luis; Joubert, P.; Gamache, Robert R.; Hartmann, Jean‐Michel

doi:10.1016/j.jqsrt.2007.03.009

Cited by 63 publications

(42 citation statements)

References 38 publications

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“…This evolution of W with L / D has already been observed for other molecular systems. [19][20][21][48][49][50] On the opposite, the value of W strongly depends on the line, W being larger for high rotational quantum numbers, in consistency with the results of Fig. 6 where deeper Dicke minima are observed for high J.…”

Section: Comparison Between Measured and Cmds-calculated Spectralsupporting

confidence: 90%

Spectral shapes of Ar-broadened HCl lines in the fundamental band by classical molecular dynamics simulations and comparison with experiments

Doménech

2014

The Journal of Chemical Physics

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Spectral shapes of isolated lines of HCl perturbed by Ar are investigated for the first time using classical molecular dynamics simulations (CMDS). Using reliable intermolecular potentials taken from the literature, these CMDS provide the time evolution of the auto-correlation function of the dipole moment, whose Fourier-Laplace transform leads to the absorption spectrum. In order to test these calculations, room temperature spectra of various lines in the fundamental band of HCl diluted in Ar are measured, in a large pressure range, with a difference-frequency laser spectrometer. Comparisons between measured and calculated spectra show that the CMDS are able to predict the large Dicke narrowing effect on the shape of HCl lines and to satisfactorily reproduce the shapes of HCl spectra at different pressures and for various rotational quantum numbers.

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Section: Comparison Between Measured and Cmds-calculated Spectralsupporting

confidence: 90%

Spectral shapes of Ar-broadened HCl lines in the fundamental band by classical molecular dynamics simulations and comparison with experiments

Doménech

2014

The Journal of Chemical Physics

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“…The standard deviation of the residuals is around 2 × 10 −4 and corresponds to the noise level of the measured beam transmission. These residuals do not show any W structure, which is observed when the VP is fitted to transitions exhibiting non-Voigt effects such as Dicke narrowing and/or speed-dependent effects (Dicke, 1953;Rautian and Sobel'man, 1967;Tran et al, 2007;Boone et al, 2007). Defining the spectrum signal-to-noise ratio (SNR) as the peak absorbance divided by the baseline standard deviation, we find a maximum SNR of approximately 65 : 1.…”

Section: Introductionmentioning

confidence: 80%

Intercomparison of in situ water vapor balloon-borne measurements from Pico-SDLA H<sub>2</sub>O and FLASH-B in the tropical UTLS

et al. 2016

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Abstract. In this paper we compare water vapor mixing ratio measurements from two quasi-parallel flights of the Pico-SDLA H 2 O and FLASH-B hygrometers. The measurements were made on 10 February 2013 and 13 March 2012, respectively, in the tropics near Bauru, São Paulo state, Brazil during an intense convective period. Both flights were performed as part of a French scientific project, TRO-Pico, to study the impact of the deep-convection overshoot on the water budget. Only a few instruments that permit the frequent sounding of stratospheric water vapor can be flown within smallvolume weather balloons. Technical difficulties preclude the accurate measurement of stratospheric water vapor with conventional in situ techniques. The instruments described here are simple and lightweight, which permits their low-cost deployment by non-specialists aboard a small weather balloon. We obtain mixing ratio retrievals which agree above the coldpoint tropopause to within 1.9 and 0.5 % for the first and second flights, respectively. This level of agreement for balloonborne measured stratospheric water mixing ratio constitutes one of the best agreement reported in the literature. Because both instruments show similar profiles within their combined uncertainties, we conclude that the Pico-SDLA H 2 O and FLASH-B data sets are mutually consistent.

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“…The W-shaped residuals arise, and their amplitude may reach 10 % of the peak absorption [16,20], as the observed lines are typically higher and narrower than predicted by the VP. Deviations from the VP are generally ascribed to the effect of velocity changes (VCs) due to collisions, which reduce Γ D , and/or to the speed dependence (SD) of the relaxation rates, which corrects the simple Lorentzian shape for different velocity-classes of active molecules.…”

Section: Introductionmentioning

confidence: 90%

“…However, a high-quality fit to a set of spectral lines is not a guarantee of the validity of the line-shape model used; in particular, in the binary-collision regime the fitted parameters have to be linear functions of the pressure [15,16,[34][35][36]. At the same time, multispectral fits [37,38] of lines recorded at several pressures of the perturbing gas are particularly useful for testing and characterizing complicated line-profile functions.…”

Section: Line-profile Models: a Brief Reviewmentioning

confidence: 99%

“…The Boone-Walker-Bernath algorithm [19] allows the calculation of a SDVP from two VPs. Ascribing the line narrowing solely to the VC-collisions frequently leads to aberrant values of the ν VC parameter which can show unrealistic non-linearities as a function of pressure [15,16]. For example, when just the linear part of this pressure-dependence is used with a GP to deduce the narrowing coefficient (the slope), the latter demonstrates higher values than those allowed by the kinetic diffusion [35,36]; conversely, a similar analysis using a RP leads to smaller values of ν VC [15].…”

Section: Acronymmentioning

confidence: 99%

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Recommended isolated-line profile for representing high-resolution spectroscopic transitions (IUPAC Technical Report)

Tennyson

Bernath

Campargue

et al. 2014

Pure and Applied Chemistry

239

106

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Abstract:The report of an IUPAC Task Group, formed in 2011 on "Intensities and line shapes in high-resolution spectra of water isotopologues from experiment and theory" (Project No. 2011-022-2-100), on line profiles of isolated high-resolution rotational-vibrational transitions perturbed by neutral gas-phase molecules is presented. The well-documented inadequacies of the Voigt profile (VP), used almost universally by databases and radiative-transfer codes, to represent pressure effects and Doppler broadening in isolated vibrationalrotational and pure rotational transitions of the water molecule have resulted in the development of a variety of alternative line-profile models. These models capture more of the physics of the influence of pressure on line shapes but, in general, at the price of greater complexity. The Task Group recommends that the partially Correlated quadratic-Speed-Dependent Hard-Collision profile (pCqSD-HCP) should be adopted as the appropriate model for high-resolution spectroscopy. For simplicity this should be called the Hartmann-Tran profile (HTP). The HTP is sophisticated enough to capture the various collisional contributions to the isolated line shape, can be computed in a straightforward and rapid manner, and reduces to simpler profiles, including the Voigt profile, under certain simplifying assumptions.

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Collisional parameters of H2O lines: Velocity effects on the line-shape

Cited by 63 publications

References 38 publications

Spectral shapes of Ar-broadened HCl lines in the fundamental band by classical molecular dynamics simulations and comparison with experiments

Spectral shapes of Ar-broadened HCl lines in the fundamental band by classical molecular dynamics simulations and comparison with experiments

Intercomparison of in situ water vapor balloon-borne measurements from Pico-SDLA H<sub>2</sub>O and FLASH-B in the tropical UTLS

Recommended isolated-line profile for representing high-resolution spectroscopic transitions (IUPAC Technical Report)

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Collisional parameters of H2O lines: Velocity effects on the line-shape

Cited by 63 publications

References 38 publications

Spectral shapes of Ar-broadened HCl lines in the fundamental band by classical molecular dynamics simulations and comparison with experiments

Spectral shapes of Ar-broadened HCl lines in the fundamental band by classical molecular dynamics simulations and comparison with experiments

Intercomparison of in situ water vapor balloon-borne measurements from Pico-SDLA H&lt;sub&gt;2&lt;/sub&gt;O and FLASH-B in the tropical UTLS

Recommended isolated-line profile for representing high-resolution spectroscopic transitions (IUPAC Technical Report)

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Intercomparison of in situ water vapor balloon-borne measurements from Pico-SDLA H<sub>2</sub>O and FLASH-B in the tropical UTLS