Analytical-function correction to the Hartmann–Tran profile for more reliable representation of the Dicke-narrowed molecular spectra

• Published in: Journal of quantitative spectroscopy & radiative transfer 2020-02, Vol.242, p.106784, Article 106784
• Main Authors: Konefał, M., Słowiński, M., Zaborowski, M., Ciuryło, R., Lisak, D., Wcisło, P.
• Format: Article
• Language: English
• Subjects: Atmospheric molecular systems; Hartmann–Tran profile; HTP; Optics; Physics; Speed-dependent billiard-ball profile; Velocity-changing collisions; β correction
• ISSN: 0022-4073; 1879-1352
• DOI: 10.1016/j.jqsrt.2019.106784

•Introduction of an analytical-function correction to the frequency of the velocity-changing collision parameter in the Hartmann–Tran profile.•The correction is called the β correction.•The βHTP is an approximation of the partially correlated quadratic speed-dependent billiard-ball profile.•The β correction is particularly important for the analysis of high-resolution spectra influenced by the Dicke narrowing. The β-corrected Hartmann–Tran profile (HTP) constitutes an approximation of the partially correlated quadratic speed-dependent billiard-ball profile (SDBBP) easily applicable in calculations. We extend the approach originally developed for self-perturbed molecules [Wcisło et al. J. Quant. Spectrosc. Radiat. Transf. 177, 75–91 (2016)] to systems with a wide range of perturber-to-absorber mass ratios, including those relevant for atmospheric studies. This approach combines the computational simplicity of the HTP with the more physically justified rigid-sphere model for velocity-changing collisions. It is important for the analysis of high-resolution spectra influenced by the Dicke-narrowing effect. The β-corrected HTP enables high quality analytical representation of experimental spectra without incurring the high computational cost of more advanced line-shape models. This correction is directly applicable to any other line-shape model based on the hard-collision model for velocity-changing collisions.