Fully quantum calculations of the line-shape parameters for the Hartmann-Tran profile: a CO-Ar case study

Grzegorz Kowzan (1) , Piotr Wcisło (1) , Michał Słowiński (1) , Piotr Masłowski (1) , Alexandra Viel (2) , Franck Thibault (2)

1 Nicolaus Copernicus University [Toruń]
2 IPR - Institut de Physique de Rennes

We present a procedure for generating the parameters of the Hartmann-Tran profile (HTP) from purely first principles calculations. Starting from an absorber-perturber interaction potential, we calculate S-matrices describing the effect of collisions on the absorbing molecule. We then use the generalized Hess method to calculate speed-dependent pressure shift and broadening parameters, and the complex Dicke parameter, ν opt , which accounts for such effects as the Dicke effect and correlations between dephasing and velocity-changing collisions. Based on these ab initio results, we derive the Hartmann-Tran profile parameters and evaluate the validity of the quadratic approximation of speed dependence and the hard-collision model of velocity-changing collisions adopted in the Hartmann-Tran profile. We also discuss the interpretation and speed dependence of ν opt. Finally, we evaluate the approximation scheme for temperature dependence of HTP line-shape parameters adopted in the 2016 edition of the HITRAN database.

Mots clés: Atomic and molecular collisions; Quantum dynamics; Molecular physics; Line profiles; Spectroscopy

Domaines: Physique [physics]

Grzegorz Kowzan, Piotr Wcisło, Michał Słowiński, Piotr Masłowski, Alexandra Viel, et al.. Fully quantum calculations of the line-shape parameters for the Hartmann-Tran profile: a CO-Ar case study. Journal of Quantitative Spectroscopy and Radiative Transfer, 2020, 243, pp.106803-1-13. ⟨10.1016/j.jqsrt.2019.106803⟩. ⟨hal-02415292v2⟩