Ab initio quantum calculations of collisional effects in molecular spectra

H Jóźwiak,P Wcisńo,N Stolarczyk,F Thibault

doi:10.1088/1742-6596/1412/13/132040

Abstract

SynopsisWe present the methodology of obtaining the dataset of the beyond-Voigt line-shape parameters for spectroscopic databases from fully ab initio quantum-scattering calculations. It provides not only the pressure broadening and shift coefficients, but also their speed dependencies and the complex Dicke parameter. This approach is based on the calculations of the generalized spectroscopic cross section, resulting from the close-coupling equations solved for a given scattering system. The calculations were validated on accurate experimental spectra of the helium-perturbed hydrogen molecule.

Highlights

The collisions manifest themselves as a perturbation of the spectral line shapes. Proper treatment of these effects is crucial in the interpretation of highly accurate molecular spectra [1], analyses of the planetary atmospheres [2, 3] or studies of ab initio molecular interactions [4, 5, 6, 7]
We present a new methodology of obtaining the line-shape parameters beyond the Voigt profile, based on ab initio quantum-scattering calculations
The process begins with the ultraaccurate potential energy surface (PES), calculated by means of the state-of-art quantum chemistry methods [5, 7]

Summary

Introduction

The collisions manifest themselves as a perturbation of the spectral line shapes. Proper treatment of these effects is crucial in the interpretation of highly accurate molecular spectra [1], analyses of the planetary atmospheres [2, 3] or studies of ab initio molecular interactions [4, 5, 6, 7]. A new structure of the most commonly-used spectroscopic database HITRAN [1, 8] has been proposed, enabling the beyond-Voigt line-shape effects to be represented.

Results

Conclusion