Локализованные состояния π-электронов в спектре оптического поглощения высокотетраэдрического аморфного углерода

Abstract

The paper presents result of ab initio methods exploiting to calculate the molar extinction spectrum of some model clusters, the molecular hybrid C24H30 included. Based on the comparison of the calculation with the experimental spectra of the main allotropic modifications of carbon, the absorption maximum with an energy of ~ 6 eV in the absorption spectrum of highly tetrahedral amorphous carbon (tа-C) attributed to the π → π * optical transitions of electrons in a single aromatic ring. The edge sites of the ring covalently bonded with the sp3 hybridised carbon atoms of the amorphous matrix. The manifestation of a shoulder in the spectrum of the imaginary part of the refractive index of a film of highly tetrahedral amorphous carbon (tа-C), 4.6 eV, is assigned to π → π * optical transitions of clusters distorted with hybrid Stone-Wallace-like defect, also covalently bonded with the amorphous matrix. Key words: interaction of light with matter, new forms of carbon, tetrahedrally coordinated amorphous carbon, Stone–Wales defect