software to fit optical spectra - Quantum Materials Group

Figure 3-28 The fitting of the reflectivity spectrum at 4 K with a three-oscillator model.
Now we can proceed with a programming. A macro should first fit the spectrum at the
lowest temperature (4 K); then it should fit the next spectrum (100 K), using the 4K parameter
values as an initial approximation; then fit the 150 K spectrum, and so forth. On each step it
must save the model parameters and export some model curves (for instance, the reflectivity or
the optical conductivity) that can be plotted afterwards using any scientific graphics package
(e.g., Origin).
To run a cycle we will need the text file “LOOP.DAT”, each line of which corresponds to
one particular temperature (see Listing 2). More exactly, each line contains a particular version
of the changeable (temperature-dependent) part of the data file name. I have already made this
file for you, but you can also create it with any standard text editor.
004
100
150
180
200
210
220
230
240
250
300
Listing 2 File “LOOP.DAT” specifies the macro cycle.
The macro itself, which is called “FITALL.RFS” is shown in the Listing 3.
Guide to RefFIT Page 46