## 3 Results and Discussion  
### X-Ray Diffraction  
Fullerene C\({}_{60}\) crystallizes in a face-centered cubic (CFC) structure, corresponding to the space group Pa-3, as shown on Figure 2. This figure shows the X-ray diffraction pattern of the pristine fullerene (as reference) and C\({}_{60}\) thin films synthesized by UCBD. According to JCPDS data [96-901-1581], the observed diffraction peaks in XRD patterns are well matched with cubic CFC structure. The configuration of the peaks suggests the presence of high crystallinity structure. The primary diffraction peaks for C\({}_{60}\) are observed at 20 positions such as ((111), 10.97\({}^{\circ}\)), ((220), 17.83\({}^{\circ}\)), ((311), 20.91\({}^{\circ}\)), ((222), 21.87\({}^{\circ}\)), ((331), 27.55\({}^{\circ}\)), ((420), 28.27\({}^{\circ}\)), ((422), 31.03\({}^{\circ}\)), and ((511), 32.97\({}^{\circ}\)). Indeed, as long as the deposition takes place, the peaks of the thin film deposed are closer to those of the pristine material (C\({}_{60}\) powder). In addition, the peaks that designate the functionalizations have disappeared. The preferential orientation peak with high intensity for pristine is (111), located at 10.97\({}^{\circ}\), while in the thin film (C\({}_{60}\)-3h, C\({}_{60}\)-5h, and C\({}_{60}\)-8h) it is located at 2\(\theta\) = 21.43\({}^{\circ}\), representing the (222) reflection plane in the C\({}_{60}\) cubic structure. Further, emergence of small peaks is noticed at 10.84\({}^{\circ}\), 17.74\({}^{\circ}\), and 20.80\({}^{\circ}\), corresponding to the (111), (220), and (311) planes of the cubic phase, respectively. The peaks marked with asterisk are additional diffraction peaks, appearing for the C\({}_{60}\)-3h, C\({}_{60}\)-5h, and C\({}_{60}\)-8h samples. These peaks agree with the vinyl stearate structure (C\({}_{20}\)H\({}_{38}\)O\({}_{2}\)) according to the information provided in the JCPDS data [00-024-1980]. These peaks prove the presence of functionalization, which is mostly the outcome of interaction involving the two solvents (toluene and 2-methoxyethanol) and the fullerene under ambient temperature. This functionalization can help the adhesion between the deposed film and the substrate. It is also depicted that the peak intensity significantly increased in the C\({}_{60}\)-8h sample compared to C\({}_{60}\)-3h and C\({}_{60}\)-5h samples; this is attributed to the increased thickness of the C\({}_{60}\) thin film. The proposed molecular structures of the C\({}_{60}\) powder and the films were obtained by Vesta (a 3D visualization program) after Rietveld refinement and assisted by Full-proof Software 5.20, as presented in Figure 3.  
From Figure 3, one can see that there is no bonding between the molecules in the proposed molecular structure of the C\({}_{60}\) powder, while in the thin film C\({}_{60}\)-8h, the bonding is formed. The two molecules are bonded between the pentagon of the right and left molecules. Each of the four neighbor molecules bond between them, and they are all able to geometrically bond to the neighboring molecules under a crystalline FCC structure. The C\({}_{60}\) dimer, which is the distance between two C\({}_{60}\) covalently bonded molecules, is calculated. For instance, between molecule C32 from the (021) plane and the molecules from the (011) plane (C31, C34, and C21), the distances are 1.7202 (A), 1.7979 (A), and 1.8803 (A), respectively, as presented in Figure 4.  
Figure 2: XRD response of thin film proposed by UCBD during different deposition periods (the asterisk (\(\bigstar\)) present the additional phase (vinyl stearate structure)). of the intrinsic strain effect and the crystallite size effect [50,51].