Figure 11

Dispersion of the linearity (R2—defined in Eq. 5) of the complex refractive index (both n and k spectra) with the concentration. The curves of different colors on the top graph correspond to different \(p_H/p\) values. The highlighted photon energies are the following: \(A=1.01\) eV, \(B=1.96\) eV, \(C=3.14\) eV and \(D=5.56\) eV. The grey areas show the photon energy range of linear behavior of the real and imaginary parts of the complex refractive index for each sample.