# Micro-Raman Spectroscopy of Dental Implants Subjected to Different Surface Treatments
## 3 Results
Furthermore, one can appreciate in the region between 400 and 700 cm\({}^{-1}\) the presence of weak and broadened Raman structures, in just the energy region where other E\({}_{\text{g}}\) modes and, in particular, A\({}_{\text{1g}}\) stretching modes of anatase are expected. Therefore, it is possible to say that the applied anodization procedures cause a further development of the oxide layer; we can also infer that the disorder tends to decrease, and, even if a good crystal quality is far from being achieved, as evidenced by the very low Raman band intensities and the observed broadening, it is likely that highly distorted TiO6 octahedra tend to be assembled on a long range scale. It is interesting to evaluate if this highly disordered TiO\({}_{2}\) oxide layer was affected by the plasma treatment. Figure 1c shows the room-temperature Raman signals of the same samples previously described, but in this case each sample has undergone the final LPP decontamination treatment. It could be claimed that the plasma treatment does not lead to any significant change in the surface, except for blasted and etched surfaces. By directly comparing the samples that differ only in the plasma process, some assessments could be done. In Figure 1d,e, respectively, a comparison between the Raman spectra of N4 and N4A, and of N5 and N5A samples is shown. As regards N4 and N4A samples, it is possible to appreciate an increase in the Raman yield after plasma treatment, probably due to the presence of an amorphous TiO\({}_{2}\) phase. The same thing is not verified for N5 and N5A samples; in this regard, it is reasonable to conclude that the amorphous TiO\({}_{2}\) phase is promoted by the anodizing process, the plasma treatment being ineffective on an already anodized surface. Thus, the anodized surface, regardless of the occurrence of CP treatment, is characterized by the presence of highly disordered TiO\({}_{2}\) phase. We tried to evaluate the degree of disorder of the TiO\({}_{2}\) layer by analyzing the Raman linewidth of the low energy mode for sample N5. In Figure 2a, the Raman spectrum from the top of the sample N5 is reported in the range 100-750 cm\({}^{-1}\). The rough data have previously been subtracted from by the correct background. Indeed, some ripples visible in Figure 1a are here absent. We then performed a best-fitting procedure using as the fitting function a sum of three Lorentzian curves and one Gaussian curve. Raman activity from an ordered structure gave rise to Lorentzian-shaped bands with the linewidth as a marker of crystalline quality. The lower the value of the linewidth, the higher the crystalline quality. Gaussian curves are instead commonly used in Raman spectra to consider the effect of diffuse disorder in the studied solid oxide, regardless of the source and nature of the disorder. The best-fitting procedure made it possible to satisfactory interpolate the experimental data with the evidence of a Gaussian component with an integrated intensity greater than the sum of the three Lorentzian curves. The Gaussian is centered at around 200 cm\({}^{-1}\) while the Lorentzian curves are peaked at around 148, 419 and 600 cm\({}^{-1}\). The lower energy component is clearly a signature of the E\({}_{\text{g}}\) mode in the anatase structure. It is difficult to attribute the other component due to the highly defective system. In any case, we observe an intense, highly broadened Raman response extending beyond 500 cm\({}^{-1}\), displaying a Gaussian behavior on which three Lorentzian modes emerge, of which the first, at 148 cm\({}^{-1}\), is the most intense. In addition, from the estimation of the linewidth of the E\({}_{\text{g}}\) mode at lower energies, we can further obtain information about the disorder affecting that part of the TiO\({}_{2}\) oxide layer which can be considered anatase-like. In Figure 2b the linewidths derived from the best-fitting procedure are plotted. On the x axis there are the points from the sample, N5.