Spectroscopies on Carbon Nanotubes

In a spectroscopy experiment, radiation is used as a probe of the properties of a system. A typical experiment of spectroscopy is schematized in Fig. 5.1. The source (probe) can be X-rays, laser light (visible and infrared radiations), neutrons, electrons,.... A monochromatic radiation is obtained by using a relevant monochromator device. As long as the response of the material to the radiation is linear, the function which describes the interaction is called the response function and it can be calculated using the linear response model. This response function x(Q, ω) relates the field associated with the source, E(Q,ω) to the response of the system, R(Q,ω) R(Q,ω)=Χ(Q,ω)E(Q,ω) (5.1) The response of the system is analyzed by a spectrometer and sent in appropriate detector and acquisition systems. The different elements of the experimental setup - monochromator, spectrometer, detector - are specific of each radiation and spectroscopy technique. In this chapter, we briefly review the concepts of the main spectroscopy techniques used in the study of carbon nanotubes. We especially focus on the spectroscopies which provide informations (i) on the vibrational modes (phonons) in carbon nanotubes, namely resonance Raman scattering, (ii) on the electronic states of carbon nanotubes, namely electron energy loss spectroscopy (EELS). We then review and discuss recent results on carbon nanotubes obtained from these techniques.