Hybrid Orbital Control in Carbon Alloys

This chapter discusses the hybridization of carbon atoms and shows that the directions of chemical bonds within a molecule cannot always be anticipated. An analytical expression for the general spⁿhybridization is also given. When a third chemical bond from two given chemical bonds is constructed in a general sp³ hybridization, there is a forbidden region of directions for the third chemical bond. The sp² hybridization of graphite can be modified to the sp³ hybridization by doping with a halogen atom. Defect states induced by structural disorder, doping and a finite crystalline size are essential to control hybridization in carbon materials. This hybridization is characterized by experimentation using a variety of spectroscopic techniques such as: the Raman scattering, the X-ray photoelectron spectroscopy (XPS), and the scanning tunnelling microscope/scanning tunneling spectroscopy (STM/STS) techniques. The Raman spectroscopy for graphite, diamond, fullerenes and carbon nanotubes is widely used for characterizations. In fullerenes, because of the high symmetry of the molecule, there exist special Raman-active modes of the molecule.