The program FitTEY is a toolbox to fit the total electron yield (TEY) or calculated spectra to off-resonant tables (optical constants delta, beta or scattering factors f1, f2) and to do Kramers-Kronig calculations in one step. Furthermore it can create new optical constants for compounds.

Usage: FitTEY is a console application.

FitTEY.exe fit mode file1 file2 element model cutmin cutmax fitmin1 fitmax1 fitmin2 fitmax2 a b c shift

This is the command and should be exactly this string

“db” or “ff” or “cF” dependent what you want to fit

• mode=“ff”: atomic conductivity to atomic scattering factor
• mode=“F” : atomic conductivity tensor to atomic scattering tensor
• mode=“db”: conductivity to refractive index

file containing the measured or calculated data dependent on the mode variable.

• mode=“ff”: filename with data to merge with columns [energy 0 conductivity]
• mode=“F” : filename with columns [energy conductivity tensor(18 entries)]
• mode=“db”: filename with data to merge with columns [energy 0 conductivity]

Look in the file formats section of this documentation for more information

File containing the off-resonant data dependent on the mode variable

• mode=“ff”: filename with columns [energy f1 f2]
• mode=“db”: filename with columns [energy delta beta]
• mode=“F” : filename with columns [energy f1 f2]

Look in the file formats section of this documentation for more information

Chemical element or Chemical formula dependent on the mode variable

• mode=“ff”: chemical element e.g. Ni
• mode=“F” : chemical element e.g. Ni
• mode=“db”: chemical formula e.g. LaNiO3

the model describes the different fitting models

In all models the parameters a acts like a scaling factor for the TEY data. The variables t is the TEY signal and the parameter e is the energy in eV.

Model D and E take the self-absorption into account. (Reiko Nakajima “Electron-yield saturation effects in L-edge x-ray magnetic circular dichroism spectra of Fe, Co and Ni” PRB Volume 59, Number 9 (1999) ) by the formulas

<m> mu lambda_e = {t sin(theta) } / {1 - t} </m> with <m> mu = 2 k_0 beta </m>

Parameter a is a scaling factor for the TEY signal. Parameter b is the escape length <m>lambda_e</m> of the electrons in Angstrom. Paramter c corresponds to the Variable <m>theta</m> and is the angle (in degrees) of the incoming beam (perpendicular incoming ray is c=90). Variable k0 is the wavenumber of the incoming ray.

Energy range in eV for the measurement which should be merged with the off-resonance data.

Energy range used for fit before resonance

Energy range used for fit after resonance

Initial value for fit parameter a. Depends on the used model. In most cases a good initial value is a = 1.

Initial value for fit parameter b Depends on the used model. Good initial starting could be b = 0.

Initial value for fit parameter c. Depends on the used model. Good initial starting could be c = 0.

Energy shift of the measurement. If unsure set it to zero.

The output of the program is a file called merged.db or merged.ff with the fitted and merged TEY-data. It is dependent on the mode variable

• mode=“ff”: filename with columns [energy f1 f2]
• mode=“db”: filename with columns [energy delta beta]
• mode=“F” : filename with columns [energy conductivity tensor(18 entries)]

To create the off resonant values of the refractive index for a compound you can use following command

FitTEY.exe create chemical_formula density shift

density of the compound in units of g/cm^3

Energy shift of the off resonant values. If unsure set it to zero.

This command converts the fitted refractive index to atomic scattering factors