Precise predictions of H2O line shapes over a wide pressure range using simulations corrected by a single measurement. (March 2018)

• Record Type: Journal Article
• Authors: Ngo, N.H.; Nguyen, H.T.; Tran, H.
• Is Part Of: Journal of quantitative spectroscopy & radiative transfer. Volume 207(2018)
• Page Start: 16
• Page End: 22
• Publication Date: 2018-03
• Subjects: Spectrum analysis -- Periodicals; Radiation -- Periodicals; Analyse spectrale -- Périodiques; Rayonnement -- Périodiques; Radiation; Spectrum analysis; Periodicals; 543.0858
• DOI: 10.1016/j.jqsrt.2017.12.014
• Languages: English
• ISSNs: 0022-4073

Abstract

Highlights: Direct calculations of N2 -boradened H2 O lines in large pressure ranges. Considerable improvement with respect to the Voigt profile. Agreement with measured absorption spectra better than 1%. Prediction of some parameters of the Hartmann–Tran profile. Abstract: In this work, we show that precise predictions of the shapes of H2 O rovibrational lines broadened by N2, over a wide pressure range, can be made using simulations corrected by a single measurement. For that, we use the partially-correlated speed-dependent Keilson–Storer (pcsdKS) model whose parameters are deduced from molecular dynamics simulations and semi-classical calculations. This model takes into account the collision-induced velocity-changes effects, the speed dependences of the collisional line width and shift as well as the correlation between velocity and internal-state changes. For each considered transition, the model is corrected by using a parameter deduced from its broadening coefficient measured for a single pressure. The corrected-pcsdKS model is then used to simulate spectra for a wide pressure range. Direct comparisons of the corrected-pcsdKS calculated and measured spectra of 5 rovibrational lines of H2 O for various pressures, from 0.1 to 1.2 atm, show very good agreements. Their maximum differences are in most cases well below 1%, much smaller than residuals obtained when fitting the measurements with the Voigt line shape. This shows that the present procedure can be used to predict H2 O line shapes for various pressure conditions and thus the simulated spectra can be used to deduce the refined line-shape parameters to complete spectroscopic databases, in the absence of relevant experimental values.