2006 APS March Meeting
Monday–Friday, March 13–17, 2006;
Baltimore, MD
Session H18: Focus Session: Carbon Nanotubes: Electronic and Optical Properties II
11:15 AM–2:15 PM,
Tuesday, March 14, 2006
Baltimore Convention Center
Room: 315
Sponsoring
Unit:
DMP
Chair: Vasili Perebeinos, IBM
Abstract ID: BAPS.2006.MAR.H18.2
Abstract: H18.00002 : Ab initio study of the optical properties of carbon nanotubes
11:51 AM–12:27 PM
Preview Abstract
Abstract
Author:
Deborah Prezzi
(CNR-INFM National Research Center S3 and Univ. of Modena and Reggio E., Italy)
We present an ab initio study of the optical properties of
carbon nanotubes. We use state-of-the-art electronic structure
methods based on many-body perturbation theory to compute
the optical absorption and resonance Raman spectra of large
tubes which have up to 200 atoms [1,2]. Our symmetry-based
method makes the study of large tubes feasible within the many-
body framework and also allows us to understand the symmetry
properties of the excitons and selection rules. We include a
study of the so-called dark excitons which are crucial for
understanding luminescence efficiency in carbon nanotubes. The
mechanism that explains the dark-bright splitting can be
understood within our symmetry-based approach. Finally, we
present an analysis of the two-photon spectra for several carbon
nanotubes, a theoretical analysis which, in conjunction with
combined one- and two-photon experiments, allows one to measure
the binding energy of excitons. We find in all cases that the
excitonic binding energy is large, ranging from 0.5 to 0.9 eV
depending on the diameter of the tube, and that the excitonic
wavefunction is Wannier-like and extended over many atoms.
Our studies for the one- and two-photon absorption and
resonance Raman spectra have been fruitful for understanding
the corresponding experiments. In particular, our theoretical
results are in good agreement with one- and two-photon
absorption experiments [3-5]. The results for resonance Raman
show that such a spectroscopic technique is a good alternative
to optical absorption since it allows for the selection of
tubes of a given diameter while probing the same excited states.
1. E.K. Chang, G. Bussi, A. Ruini, and E. Molinari,
Phys. Rev. Lett. 92, 196401 (2004).
2. E.K. Chang, G. Bussi, A. Ruini, and E. Molinari,
Phys. Rev. B 72, 195423 (2005).
3. M. Y. Sfeir et al., Science 306, 1540 (2004).
4. J. Maultzsch et al., to be published in Phys. Rev. B,
see also cond-mat/0505150.
5. Z. M. Li et. al., Phys. Rev. Lett. 87, 127401 (2001).
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2006.MAR.H18.2