What is Density of States

Carbon nanotubes have attracted the scientific community throughout the world, and in the past decade, a lot of work has been reported related with synthesis, characterization, and applications of carbon nanotubes. This chapter is written for readers who are not familiar with the basic principles of Raman spectroscopy in carbon nanotubes. The structure of carbon nanotubes, types of the carbon nanotubes, Brillouin zone of carbon nanotubes, and band structure of carbon nanotubes are discussed at length, which will serve as foundation for the study of Raman scattering in carbon nanotubes. The Density of States (DOS) of single walled carbon nanotubes are illustrated by an example which will encourage readers to calculate the DOS of any type of carbon nanotube. The Raman modes of vibration are discussed, and Raman spectroscopic analysis is presented by considering the typical spectra of single-walled carbon nanotubes.