Figure 6.

a) Difference spectra for mfps-pep-3Dopa adsorbed on TiO₂ obtained by subtracting every two consecutive normalized ATR-IR spectra in Figure 5b, showing the emergence of specific absorptions over the course of the adsorption process, i.e., aromatic ring vibrations at 1517 and 1247 cm⁻¹. The doublet due to catechol/Ti coordination bond is visible at 1487 and 1273 cm⁻¹ (in red), and the specific bonds associated with these vibrations are presented in the schematic complex structure (bonds in red). b) Evolution of the negative second-derivative spectra of mfps-pep-3Dopa adsorbed on TiO₂ from Figure 5c in the 1505−1475 and 1300−1255 cm⁻¹ spectral regions. Peaks characteristic of the catechol-Ti coordinative bond (red), intermediate surface complex (blue), and outersphere complex (black) are indicated in the figure.