# CO2 sub-Lorentzian line wings¶

HELIOS-K supports sub-Lorentzian profiles according to the $$\chi$$ factors from Perrin and Hartmann 1998. The $$\chi$$ factors are specified in the files chiPH89__CO2-CO2.dat and chiPH89__CO2-N2.dat. In these files, the affected wavenumber range can be set. The param.dat file contains the option subLorentzianfile, where the file name of the used $$\chi$$ factors file can be set. If a filename is set there, the sub-Lorentzian line wings are enabled.

In principle, the $$\chi$$ factors can be applied also to other molecules than CO2, but this is not recommended to do.

M.Y.Perrin and J.M.Hartmann, 1988 (TEMPERATURE-DEPENDENT MEASUREMENTS AND MODELING OF ABSORPTION BY CO2-N2 MIXTURES IN THE FAR LINE-WINGS OF THE 4.3 # m CO2 BAND).

In Fig. 2 is shown an example of the sub-Lorentzian profile for CO2.

Relevant parameters for full Voigt:
• doStoreFullK = 1

• cutMode = 0

• cut = 25.0

• profile = 1

• subLorentzianfile = -

Relevant parameters for sub-Lorentzian Voigt profile in specific wavenumber band:
• doStoreFullK = 1

• cutMode = 0

• cut = 25.0

• profile = 1

• subLorentzianfile = chiPH89__CO2-CO2.dat

• in chiPH89__CO2-CO2.dat:
• range in cm^-1

• 2100 2500

Relevant parameters for sub-Lorentzian Voigt profile in the full wavenumber range:
• doStoreFullK = 1

• cutMode = 0

• cut = 25.0

• profile = 1

• subLorentzianfile = chiPH89__CO2-CO2.dat

• in chiPH89__CO2-CO2.dat:
• range in cm^-1

• 0 10000

Fig. 2 CO2 sub-Lorentzian wings with $$\chi$$ factors for Perrin and Hartmann 1998. Top panel,: $$\chi$$ factors applied to the band 2100-2600 cm^-1. Bottom panel: $$\chi$$ factors applied to the full wavenumber range. CO2, Hitran 2016, T = 250 K, P = 2 atm.