Abstract

Using femtosecond pump probe spectroscopy with sub-20 fs resolution, we probe fundamental properties of the E₁₁ exciton in (6,5) single walled carbon nanotubes, prepared by density gradient ultracentrifugation [1]. From the initial photobleaching (PB) signal, measured faster than any relaxation process, we obtain the one-dimensional electron-hole correlation length ("exciton size") of the excitonic wavefunction along the nanotube. Anisotropy measurements in highly purified samples show that there is virtually no depolarisation of the E₁₁ bleach over 40 ps. A photoinduced absorption (PA) band, blueshifted against the E₁₁ bleach, shows only weak anisotropy. We discuss the origin of this PA band.

© 2009 IEEE