The standard D-G-2D pattern of Raman spectra of sp² amorphous carbons is considered from the viewpoint of graphene domains presenting their basic structure units (BSUs) in terms of molecular spectroscopy. The molecular approximation allows connecting the characteristic D-G doublet spectra image of one-phonon spectra with a considerable dispersion of the C=C bond lengths within graphene domains, governed by size, heteroatom necklace of BSUs as well as BSUs packing. The interpretation of 2D two-phonon spectra reveals a particular role of electrical anharmonicity in the spectra formation and attributes this effect to a high degree of the electron density delocalization in graphene domains. A size-stimulated transition from molecular to quasi-particle phonon consideration of Raman spectra was experimentally traced, which allowed evaluation of a free path of optical phonons in graphene crystal.

This paper presents the results of investigations of the electrical conductive properties with a nanoscale locality at nanoampere currents and the results of an analysis of the correlation between the

The progress in the practical use of glassy carbon materials has led to a considerable interest in understanding the nature of their physical properties. The electrophysical properties are among the most demanded properties. However, obtaining such materials is associated with expensive and dirty processes. In nature, in the course of geological processes, disordered sp² carbon substances were formed, the structure of which is in many respects similar to the structure of glassy carbon and black carbon, and the electrical properties are distinguished by a high-energy storage potential and a high efficiency of shielding electromagnetic radiation. Given the huge natural reserves of such carbon (for example, in the shungite rocks of Karelia) and the relative cheapness and ease of producing materials from it, the study of potential technological applications and the disclosure of some unique electrophysical properties are of considerable interest. In this paper, we present an overview of recent studies on the structure, electrophysical properties, and technological applications of natural disordered sp² carbon with the addition of novel authors’ results.