## 1 Introduction  
In this work, for the first time, comprehensive studies of the fullerite C\({}_{60}\) modified by hot isostatic pressing (HIP) were carried out using a complementary set of methods that are informative at the nano and micro levels of the structure of matter. Studies of the behavior of the molecular fullerene C\({}_{60}\) and its condensed phase, fullerite, at high pressures and temperatures began in the mid-1990s, when simple methods for producing C\({}_{60}\) were proposed and it became available in gram quantities [1, 2, 3]. Various polymer phases of C\({}_{60}\) and their changes at temperatures above the limit of thermal stability of C\({}_{60}\) were studied [4, 5, 6, 7, 8]. The investigations of the fullerene C\({}_{60}\) transformations at high static and dynamic pressures at temperatures above the thermal stability limit of C\({}_{60}\) molecular clusters [9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20] showed great opportunities for the creation of new carbon materials with a wide variety of physicochemical properties. As a result, sufficiently detailed phase diagrams of the fullerene C\({}_{60}\) were obtained, especially at the pressure above 1 GPa [21, 22, 23].  
At the same time, studies on the intercalation of various gases into the fullerite lattice in gasostats (devices allowing to create high gas pressures up to 300 MPa) at high temperatures (more than 1770 K) were conducted. It was shown, for example, that at temperatures of 400-500 K and the limiting pressures Ar, Xe and Kr fill fullerite octahedral voids, while its face-centered cubic (fcc) structure is preserved [24, 25]. Studies of the fulleritebehavior at pressures of 0.1-1.5 GPa and temperatures above the collapse temperature of the C\({}_{60}\) molecule [7; 16] showed that the resulting disordered nanocarbon phase has unique properties such as high hardness and elasticity at a density lower than that of graphite. Therefore, finding and describing the structural and electron characteristics of fullerite under different external conditions is an important task. In the available works, as a rule, data obtained by separate methods for certain values of pressures and temperatures are given. At the same time, there are no data on XPS and NEXAFS studies of HIP-treated fullerene C\({}_{60}\). This does not allow the objective characterization of the process of the fullerite modification and reliably determines the atomic chemical composition and structure of the final product. It is obvious that further serious progress in the study of solid-phase transformations of C\({}_{60}\) is impossible without the use of the modern methods of studying the atomic-electronic properties of such polyatomic systems. The complexity of the nanoscale atomic-electron structure of such materials requires the use of the combination of the complementary research methods. These methods should be highly informative at the nanoscale, non-destructive and highly sensitive to the sample atomic structure and its changes due to physical and chemical influences. The near edge X-ray absorption fine structure (NEXAFS) spectroscopy [26] and X-ray photoelectron spectroscopy (XPS) [27; 28] are effective experimental methods that allow us to directly obtain detailed information about the nanoscale atomic-electron structure of the polyatomic system under study. Their combination with traditional Raman spectroscopy and X-ray diffractometry (XRD) provides new reliable knowledge about the atomic and electronic structure of nanostructured carbon materials [29; 30]. In this work, the successive modification of fullerite C\({}_{60}\), as a result of HIP at a pressure of 0.1 GPa in an argon atmosphere in the temperature range of 920-1270 K, was characterized by XRD, XPS, NEXAFS and Raman spectroscopy. The study showed that changes in X-ray diffraction patterns, C 1s NEXAFS and Raman spectra appear simultaneously due to structural changes in the fullerite C\({}_{60}\) with increasing temperature during HIP treatment.