Ultrafast pump probe spectroscopy of single-wall carbon nanotubes

Abstract

This dissertation is mainly focused on the femtosecond pump probe spectroscopy of the (6, 5) single wall carbon nanotubes (SWNTs). There are three advantages in this experiment, first, we upgrade the optical parametric amplifier (OPA) in the laser system to allow automatic wavelength tuning of the OPA; second, we tune the excitation wavelength continuously across the E22 exciton resonance of the (6, 5) tube to examine the dynamics at the E11 and E22 states; third, we use highly purified chirality enriched SWNT samples. These advantages allow us to obtain the spectroscopy with unprecedented details, which greatly help to improve our understanding of the two fundamental issues in SWNT pump probe spectroscopy, for the excited state dynamics, we are able to separate a short time dynamics from a long time dominant 1D diffusion process in the (6, 5) tube and relate this short time process to the carrier dynamics on the E11 state; for the photoinduced absorption, we are able to compare it with the phonon sideband features in the photoluminescence excitation spectrum and propose a new mechanism for its origin, the phonon assisted carrier scattering to the Eii states.