[Ifeffit] energy resolution

[Lisa Bovenkamp]

Hello all.
I am getting confused with different comments how to determine the energy resolution
of an XAS beamline.
I think using peak fitting to determine the line width is a reasonable method.
The basis of a XAS peak is the Voigt profile (a combination of a Lorenzian and Gaussian)
The width of the Lorenzian equals the natural line width
while the width of the Gaussian represents the experimental line width and some features
Now here is question 1: 
What is the combination of the two profiles in the Athena peak fitting routine for the Pseudo-Voigt?
Question 2:
Is the sigma (Gaussian width) that delta E that represents
the resolution - (E /delta E) ?

Using a different program (Igor Pro) to determine 
the width gives different results because can only 
use a simple combination of Lorentz and Gauss (1:1).

Thanks.
Lisa