Comparative Raman spectroscopy study of Single-Wall and Double-Wall carbon nanotube systems doped with $H_2SO_4$

In this work, we performed Raman experiments on a mixture of Single-wall and Double-wall carbon nanotubes for different relative concentrations and using different laser energies. Two sets of samples were analyized, one which was exposed to $H_2SO_4$ for 5$s$ and one which is pristine. The $H_2SO_4$ is known to act as an acceptor for the electrons of graphitic materials. The effect of the hole doping on the vibrational and electronic properties of the double and single-wall carbon nanotubes is probed using Resonant Raman scattering with different excitation energies probing different nanotubes. The inner and outer walls of double-wall nanotubes can also be studied at the same time for selected excitation energies. A detailed analysis of the charge transfer in single wall and double wall nanotubes and its effects on the nanotube properties is obtained.