Finally we want to determine orientation angles from experimental data. Using the model developed in the previous three steps we try to 'fit' the angle to reproduce the spectra tu2_ex2_20.spc, tu2_ex2_40.spc, tu2_ex2_60.spc and tu2_ex2_80.spc that are delivered with this tutorial. Although these spectra have been simulated for simplicity you should import them as experimetal data.

We suppose that the thickness of the molecular layer is also unknown and select this quantity as second fit parameter.

The list of fit parameters is now this:

Simply start the automatic fit and find the values 20° and a thickness of 0.65 microns:

The final configuration of this example is found as tu2_ex2_step4.sc2 in the directory of this tutorial.