Figure 1.

(a) Normalized micro−Raman spectra of substrate A along the diameter in the range 925–1100 cm⁻¹. (b) Normalized micro−Raman spectra of substrate B along the diameter in the range 925–1100 cm⁻¹. The spectra are normalized to the TO band at 780 cm⁻¹ amplitude. The graphical representations of the substrates are inserted in both panels. The color of the spectra refer to the positions where they were acquired, which are marked by an x of the same color on the graphical representation.