Photo-physics of carbon nanotubes
When: May 1, 2007 (Tue), 03:30PM to 04:30PM
Hosted by:
Ophelia Tsui
Speaker: Anna Swan, Boston University
This event is part of the Department Colloquia Series. Colloquia are at 3:30 in the Metcalf Science Center (SCI 107) Refreshments will be served at 3:15 in the 1st Floor Lounge
Carbon nanotubes have attracted a lot of interest since their discovery in 1991 for their extreme physical properties such as their strength and flexibility and excellent thermal and electrical conductivity. Of particular interest here are the electronic properties. The electronic band-structure is strongly affected by small changes in diameter and chirality variation, producing both metallic nanotubes with linear electron (Dirac) dispersion or semiconducting nanotubes with varying band gaps. The optical properties were recently found to be dominated by excitons with binding energies several order of magnitudes larger than in a bulk semi-conductor. The semiconducting nanotubes should be ideal as variable wavelength nano-light emitters, but it has been quite tricky to achieve high quantum efficiency light emission due to both environmental effects and intrinsic factors. I will discuss our recent results on exciton screening and how it affects the optical and electronic properties and intrinsic interactions betweens electrons and phonons in a single nanotube that are fundamental to many physical behaviors, e.g transport properties and optical response.