## 3 Results and Discussion  
### Pristine Fullerite C\({}_{60}\) Study  
The results of preliminary tests of the initial powder of pristine fullerene C\({}_{60}\) by XRD, Raman, XPS and NEXAFS techniques are shown on Figure 1a\(\sim\)c and Figure 1d, respectively. The XRD patterns (Figure 1a) are in good agreement with those of the studies [34; 35; 36] and Raman spectrum (Figure 1b) show only the peaks characteristic of pure C\({}_{60}\)[37; 36; 21; 38]. Figure 1c shows the overview XPS spectra in the 0-1200 eV binding energy (BE) range for the C\({}_{60}\) powder and highly oriented pyrolytic graphite (HOPG) exposed to air for a long time. This spectrum of the C\({}_{60}\) powder contains an intense C 1s peak at 284.7 eV (full width at half maximum, FWHM is 1.3 eV) and a broader O 1s line at 532.2 eV (FWHM is 2.6 eV). In turn, the HOPG spectrum is also characterized by an intense C 1s peak at 284.6 eV (FWHM is 1.1 eV) and a broader O 1s line at 532.0 eV (FWHM is 2.4 eV). XPS measurements allow to derive an estimate of the oxygen relative atomic concentration on the C\({}_{60}\) powder surface, equal to 4%, and on the HOPG surface, equal to 8%. The availability of the O 1s peak in the overview XPS spectra of C\({}_{60}\) and HOPG indicates the presence of oxygen-containing compounds on the surface of the materials under study. Possible reasons for this could be carbon oxides, as well as water and oxygen molecules physically adsorbed from the air. The inset in Figure 1c shows C 1s and O 1s core-level PE  
spectra of C\({}_{60}\) and HOPG. In both of C 1s spectra there is only one asymmetric peak and no signals associated with carbon oxides. The main line of the C 1s core level PE spectrum of HOPG is accompanied by a noticeable tail on the high-energy side, which is caused by \(\pi\)-type shake-up satellite [39; 40; 41]. The obtained C 1s NEXAFS spectra of HOPG and C\({}_{60}\) in terms of the number of absorption bands and their energy positions are in good agreement with the results of the previous works [42; 44; 45; 46; 47; 48; 49; 50; 51], respectively. The presence of carbon oxides on the fullerite C\({}_{60}\) and HOPG surface can be detected using the C 1s NEXAFS spectra shown in Figure 1d. The energy positions of absorption bands in the C 1s NEXAFS spectrum of the fullerite C\({}_{60}\) are given in Table 1. \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline
**Peak Number** & **1** & **2** & **3** & **4** & **5** & **6** & **7** & **8** & **9** & **10** & **11** \\ \hline Photon energy, eV & 284.50 & 285.84 & 286.43 & 288.30 & 290.91 & 291.85 & 292.93 & 295.50 & 297.50 & 300.73 & -305.50 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Energy positions of absorption bands in C 1s NEXAFS spectrum of C\({}_{60}\). Figure 1: Characterization of the pristine C\({}_{60}\) powder and HOPG: (**a**) C\({}_{60}\) XRD pattern; (**b**) C\({}_{60}\) Raman spectra; (**c**) survey XPS spectra of the C\({}_{60}\) and HOPG, the inset shows their C 1s and O 1s XPS spectra; (**d**) C 1s NEXAFS spectra of the C\({}_{60}\) and HOPG (shifted at the vertical scale by 1.5 Mb). The arrow in (**d**) indicates the position of the fullerite C\({}_{60}\) C 1s absorption edge (289.60 eV) [42]. The positions of the absorption bands in the atomic groups C=O (288.9 eV), C–O–C (287.2 eV) and C–O (286.7 eV) [43] are marked with dashed lines. At room temperatures fullerene C\({}_{60}\) condenses into a molecular crystal (fullerite C\({}_{60}\)) in which the molecules are bound by weak Van der Waals forces and are in quasi-free rotational motion. This crystal has an fcc lattice with a 1.417 nm lattice constant and 1.002 nm intermolecular distance [36]. The C 1s NEXAFS studies of C\({}_{60}\) in condensed and gaseous phases [50], as well as C\({}_{60}\) molecules isolated in the Xe matrix [51] showed that intermolecular interaction in fullerite C\({}_{60}\) does not play a significant role in the formation of its electronic structure and the electron correlation effects are intramolecular.