software to fit optical spectra - Quantum Materials Group

Figure 4-2 The “Parameter control” windows contains the full information about the selected parameter.
The activity switch can be also toggled in the “Model” window by clicking right mouse
button on the parameter, or pressing SPACE when the parameter is selected.
4.4. Experimental Parameters
There is a set of parameters, which are not directly related to the model dielectric
functions, but rather to the experimental conditions. For instance, the reflectivity coefficient
depends on the angle of incidence, even though the dielectric function does not. This kind of
parameters is collected in a separate window called “Experimental parameters” (Figure 4-3). It
can be displayed by choosing the corresponding item in the “Window” menu.
Figure 4-3 The “Experimental parameters” window lists all parameters, related to the experimental conditions.
One should note that experimental parameters apply to the output quantities of the models
of the Dielectric Function type only (see section 4.6). In the case of other model types all the
parameters, necessary to calculate model outputs, are contained in the model window.
The description of all the experimental parameters is given in Table 4-1.
Parameter name Units Description
Sample thickness cm Thickness of the sample, used to calculate the coefficient of
transmission with the interference (“T”) and without the
interference “TT”.
Thickness spread - The relative spread of the sample thickness. Used to model
the effect of non-parallel (wedged) sample. Applies to the
quantities “T” and “TT”.
Angle of incidence degrees The angle of incidence. The normal incidence corresponds to
0 o , the totally grazing incidence – 90 o . Applies only to “Rp”,
“Rs” and “Rps”.
Guide to RefFIT Page 53