f1f2data

f1f2 data or f' and f" data is necessary to calculate the resonant structure factors.

Cromer Liberman (CL) f1f2

The easiest way to get CL f1f2 data is to use the "Hephaestus" program from Ifeffit: select f' & f" at the left side, type in the energy range of your RASD scans, select the smallest energy steps used in your RASD scans as energy grid, select plot both f' and f" and klick at your resonant element in the Periodic Table. Klick save data for ..., give a file name, and that's it.

You can use this file as f1f2_file in your RASD analysis.

But you can also use this file together with a XANES scan of a reference sample of your resonant element to produce experimental f1f2 data. That is especially recommended if the absorption edge of the resonant element shows a big whiteline and the shape of the experimental XANES deviates strongly from the Cromer-Liberman calculated f" as it is generated by Hephaestus.

experimental f1f2

The sxrd.f1f2.py module holds a function "sxrd.f1f2.f1f2()" you can use to calculate experimental f1f2 data. It needs the CL f1f2 data from Hephaestus and a normalized XANES scan of a reference sample of your resonant element (same oxidation state, similar speciation ...). CL f1f2 and normalized XANES should be in the same Energy range. Furthermore it needs is the theoretical edge energy, e0 in eV (integer), an energy shift between the CL data and the experimental data, e0shift (also eV, also integer), a file name for the output file (default is 'exp.f1f2'), and a number n (default is 30) which marks the number of points used at each end of the scan to match your normalized XANES to the CL f", and the range of points around e0, which are not used to match the spectra . You can run the function like this:

 sxrd.f1f2.f1f2(datafile = 'CL.f1f2' , expfile = 'XANES.nor' , e0 = 12658 , e0shift = 5 , output ='Se_exp.f1f2', n=50)

The function produces a plot of CL and experimental f1f2 data and the specified output file. It seems to work best when the start of the absorption edges of the CL and the experimental f" match as exactly as possible, you may have to play around with e0shift (and in case with the Hephaestus option to convolute your CL f1f2 with a certain energy interval).

You can then use the output of this function, e.g. 'Se_exp.f1f2' as f1f2_file in your RASD analysis.