Abstract:
The paper presents result of ab initio methods exploiting to calculate the molar extinction spectrum of some model clusters, the molecular hybrid C$_{24}$H$_{30}$ 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 $\sim$6 eV in the absorption spectrum of highly tetrahedral amorphous carbon (ta-C) attributed to the $\pi\to\pi^*$ optical transitions of electrons in a single aromatic ring. The edge sites of the ring covalently bonded with the $sp^3$-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 (ta-C), 4.6 eV, is assigned to $\pi\to\pi^*$ optical transitions of clusters distorted with hybrid Stone–Wallace-like defect, also covalently bonded with the amorphous matrix.
Keywords:interaction of light with matter, new forms of carbon, tetrahedrally coordinated amorphous carbon, Stone–Wales defect.
Fulltext:
PDF file (331 kB)