## 3 Results
### Fourier Transform Infrared Spectroscopy (FTIR) Analysis  
For the deposition with PLD method, the turmeric powder compressed into a disk shape target without any additives was used. That provides information on the starting chemical composition where the specific groups in curcuminoids are expected to be found, such as shown in the chemical formulae in Figure 4. Fourier transform infrared spectroscopy (FTIR) analysis of both target and obtained thin film resulted into spectra of high similitude (Figure 5), proving that curcuminoid-silanol films were obtained. In Figure 5, for the _Turneric_ FTIR spectrum, predominant curcumin component is observed, while for the thin film obtained by PLD (_Curcuminoid-silanol film_ spectrum), demethoxylation is evidenced by the drastic mitigation in transmittance intensity, which becomes barely visible, of the 2925 cm\({}^{-1}\) and 2853 cm\({}^{-1}\) bands specific for C-H aliphatic stretching of the acetal (methoxy) groups O-CH\({}_{3}\), indicating increase in the other two curcuminoid components (demethoxycurcumin, and bisdemethoxycurcumin). Demethoxlation is also denoted by lower intensity of bands in the thin film spectrum compared with the turmeric powder, bands corresponding to specific groups. Therefore, intensity mitigation is noticed for the 1279 cm\({}^{-1}\) band of the (ar)C-O-(al)C groups stretching asymmetric, usually vibrating in the range (1275-1200 cm\({}^{-1}\)) [16], in the same range with (ar)C-H in plane deformation vibration (1250-950 cm\({}^{-1}\)) while the (ar)C-C group expected in the range 3080-3030 cm\({}^{-1}\)[16] overlaps with the broad peak at 3440 cm\({}^{-1}\) in turmeric spectrum and it is very weak in the thin film spectrum. Moreover, a decrease of the intensity of the bands is observed for those at 1079 cm\({}^{-1}\) and 1024 cm\({}^{-1}\) in the thin film spectrum compared with the turmeric powder spectrum corresponding to (ar)C-O-(al)C stretching  
Figure 4: Chemical structures of curcuminoids. symmetric vibrations, usually occurring in the range of 1075-1020 cm\({}^{-1}\)[16]. In the same range are the specific silanol terminal groups as it is presented below. The other specific vibrations for the curcuminoids are observed in both FTIR spectra of turmeric powder and deposited thin film. It is important to notice silanol groups which are identified in both turmeric powder and thin film. Thermal resistivity of the silanol groups explains their preservation during ablation and occurrence in the deposited thin films. The band at 3848 cm\({}^{-1}\) is of O-H free stretching vibrations [17] that could be associated to Si-OH groups [18] and the 3744 cm\({}^{-1}\) band has been previously proven and reported for the terminal silanol groups [19; 20; 21], the IR spectroscopy generally assigning the bands in the range 3700-3200 cm\({}^{-1}\) to Si-OH stretching vibrations [18]. The bands at 1457 cm\({}^{-1}\) and 1279 cm\({}^{-1}\) are of the (Si-)CH\({}_{3}\) group asymmetric and symmetric, respectively, deformation vibrations [16]. The 1024 cm\({}^{-1}\) band of the Si-OH deformation vibrations (\(\sim\)1030 cm\({}^{-1}\)), but also 1079 cm\({}^{-1}\) of Si-O-Si stretching vibrations (1090-1030 cm\({}^{-1}\)) [16] are lower in intensity for the thin film than in the turmeric powder spectrum, showing that some of the silanol terminal groups are removed during ablation process. Silanol terminal groups are also evidenced with the 767 cm\({}^{-1}\) band assessed to Si-C stretching vibration in the 850-650 cm\({}^{-1}\) range and to (Si-)CH\({}_{3}\) skeletal vibration that usually occurs at \(\sim\)765 cm\({}^{-1}\)) [16]. The O-H free and H-bonded phenolic groups are evidenced by the stretching vibrations at 3440 cm\({}^{-1}\)[16]. The 3267 cm\({}^{-1}\) band indicates C-H aromatic stretching vibrations [16], aromatic character being also evidenced in the C=C aromatic skeletal vibrations of 1523 cm\({}^{-1}\) band [16].