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TU Dresden » Faculty of Mechanical Science and Engineering » Institute for Materials Science » Chair of Materials Science and Nanotechnology

Friday, 04 May 2007
(at 13:15 in room Phy 5.0.21)
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Exciton dynamics and localization in single-walled carbon nanotubes

Achim Hartschuh

Department Chemie
Ludwig-Maximilians-Universität München

We studied the dynamics of excitons in individual semiconducting single-walled carbon nanotubes (SWNTs) using time-resolved photoluminescence (PL) spectroscopy. The PL decay from nanotubes of the same (n,m) type was found to be mono-exponential, however, with lifetimes varying between less than 20 ps and 200 ps from nanotube to nanotube. Competition of non-radiative decay of excitons is facilitated by a thermally activated process, most likely a transition to a low-lying optically inactive trap state that is promoted by a low-frequency phonon mode [1]. Near-field PL imaging with a spatial resolution better than 15 nm was used to visualize the spatial extent of luminescent excited states along SWNTs. The PL from micelle-encapsulated SWNTs on mica is typically extended along the nanotube up to several hundreds of nanometers. For SWNTs on glass, we observe highly localized PL from short segments of about 20 nm in length indicating bound excitons [2].
[1] A. Hagen et al., Phys. Rev. Lett. 95, 197401 (2005)
[2] A. Hartschuh et al., Nano Lett. 5, 2310 (2005)

Brief Bio:

Prof. Achim Hartschuh studied Physics at the Universities of Tübingen and Stuttgart. After receiving his Ph.D. in 2001 he spent two years as a postdoctoral scientist at the University of Rochester, USA. From 2002 to 2006 he was Juniorprofessor at the Universities of Siegen and Tübingen. Since April 2006 he is Professor for Physical Chemistry at the LMU München. His work is focused on the development and application of novel near-field optical techniques.

Invited by C. Strunk

Within the Graduiertenkolleg Nichtlinearität und Nichtgleichgewicht in kondensierter Materie, GRK 638

last modified: 2021.10.21 Thu
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