## 2 Materials and Methods
### Characterization  
The samples were studied by set of complementary methods: X-ray diffractometry (XRD), Raman, near edge X-ray absorption fine structure (NEXAFS) [20] and photoelectron (XPS) spectroscopy [21; 22].  
The XRD analysis of materials was performed with CuK\({}_{\alpha}\)-radiation using a Bruker D8 Discover X-ray diffractometer in the \(\theta\)-2\(\theta\) geometry with a Gobel mirror, an equatorial Soller slit with the angular divergence of 2.5\({}^{\circ}\), and an exit slit of 1.5 mm. Scanning was performed in 0.02\({}^{\circ}\) increments at 2-2.5\({}^{\circ}\)/min scanning speed. The resulting diffractograms were processed with the EVA software using the PDF-2 (2012)--a database of diffraction data.  
Raman spectroscopy was conducted at room temperature in the 80-3500 cm\({}^{-1}\) interval using a Horiba-Yvon Jobin LabRam HR800 spectrometer equipped with 600 g/mm grating and Ar laser with a 1 mW and 488 nm wavelength. Lenses of 50\(\times\) and 100\(\times\) were used for analysis. The spectrometer was fitted with neutral filters to limit the laser radiation power. The spectral and spatial resolution was about 1 cm\({}^{-1}\) and 1 \(\upmu\)m, respectively. Sample damage was an issue in fullerite C\({}_{60}\) Raman measurements, so the power on the C60 sample was well below 1 mW, and its Raman spectra were measured at the minimum recording time. For HOPG, MWCNTs and CSS, registration times of up to 60 s were used with no visible damage or changes in signal shape. Raman spectra of all samples were performed at different points for each sample.  
The electronic structure of all samples was characterized by the NEXAFS spectroscopy. These studies were performed using the synchrotron radiation of the Russian-German soft X-ray beamline at BESSY II synchrotron radiation facility (Berlin, Germany). In all NEXAFS spectra measurements a total electron yield (TEY) mode was used. The energy positioning of C 1s NEXAFS spectra elements were performed using the narrow \(\uppi^{\text{e}}\)-resonance at 285.38 eV in the C 1s spectrum of HOPG [23]. The spectral dependence of photon flux was determined as a result of the division of TEY signal from clean Au photocathode and Au atomic X-ray absorption cross section [24] in accordance with [17; 25]. The photon energy resolution was better than 0.05 eV. The ex situ preparation of the samples of MWCNTs, C\({}_{60}\) and CSS for X-ray absorption measurements was performed by pressing the powder of the test material into the clean surface of an indium or copper plate in air. The sample in the form of a 2 \(\times\) 2 mm plate was attached with silver glue to the surface of the copper holder. The X-ray incidence angles were chosen between 40-50 degrees to the holder surface.  
The X-ray photoelectron studies were performed at the resource Centre \"Physical methods of surface investigation\" of the Science Park of St. Petersburg State University (St. Petersburg, Russia). XPS analysis was performed using a Thermo Scientific ESCALAB 250 Xi electron spectrometer equipped with an electron-ion charge compensation system to neutralize the sample charging during experiments. The X-ray tube with AlK\(\alpha\) radiation (1486.6 eV) was used as a source of ionizing radiation. The survey and in the are of internal shells photoelectron (PE) spectra were obtained at pass energy of 100 eV and 50 eV, respectively. The ESCALAB 250 Xi spectrometer software was used to process the experimental data.