Double Lorentzian Line Shape
The double-Lorentzian (DL) is an excellent alternative to the Doniach-Sunjic (DS) line-shape for asymmetric peaks. The DL line-shape is very similar to a Voigt function, but with the Lorentzian width different for the two sides of the peak. It has many advantages over the DS:
More details can be found in the document below.
The figure shows the best fits obtained by employing DL and DS line-shapes for a Fe 2 p spectrum. The fit is much better in the DL case even though extra physical restrictions were employed, such as that the area of the 2 p 1/2 branch is forced to be one half of the 2 p 3/2 branch.