Amorphous carbon (AC) is present in the bulk and on the surface of nanostructured carbon materials (NCMs) and exerts a significant effect on the physical, chemical and mechanical properties of NCMs. Thus, the determination of AC in NCMs is extremely important for controlling the properties of a wide range of materials. In this work, a comparative study of the effect of heat treatment on the structure and content of amorphous carbon in deposited AC film, nanodiamonds, carbon black and multiwalled carbon nanotube samples was carried out by TEM, XPS, XRD and Raman spectroscopy. It has been established that the use of the 7-peak model for fitting the Raman spectra makes it possible not only to isolate the contribution of the modes of amorphous carbon but also to improve the accuracy of fitting the fundamental G and D₂ (D) modes and obtain a satisfactory convergence between XPS and Raman spectroscopy. The use of this model for fitting the Raman spectra of deposited AC film, ND, CB and MWCNT films demonstrated its validity and effectiveness for investigating the amorphous carbon in various carbon systems and its applicability in comparative studies of other NCMs.

The results of study of the surface chemistry of nanodiamonds treated by a mixture of HClO₄ and H₂SO₂ acids are presented. Changes of the composition of surface diamond groups brought up by thermal annealing were monitored by Fourier transformed infrared spectroscopy and temperature‐programmed desorption. The decomposition of oxygen‐containing groups is observed at 300–900°C; CH_x groups decompose at 700–1150°C. The process of the annealing of ND was investigated by the X‐ray photoelectron spectroscopy. The clear onset of ND graphitization was observed at temperature of 950°C that is supported by the appearance of sp ² component in the C1s spectrum. The presence of the N1s peak in spectra of ND is observed in initial and partially graphitized ND annealed up to 1100°C.