Hannover 2013 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 23: Femtosecond Spectroscopy VI

MO 23.2: Vortrag

Donnerstag, 21. März 2013, 14:30–14:45, F 102

Singlet exciton size in (6,5) SWNTs revisited — •Christoph Mann and Tobias Hertel — Institute of Physical and Theoretical Chemistry, Julius-Maximilian University Würzburg, Germany

Single wall carbon nanotubes (SWNTs) can be thought of as one-dimensional (1D) nanostructures consisting of rolled-up graphene sheets. Because of their unique electronic, mechanical and optical properties, an understanding of the excited-state dynamics in SWNTs is of great interest for both, better insight into fundamental photophysics of 1D systems in complex environments and for optoelectronic applications. The excited state dynamics are dominated by strongly bound Wannier-Mott type excitons. The electron-hole correlation length - i. e. the exciton size - represents one of their most basic photophysical characteristics and is therefore key for a better understanding of a variety of optical properties. The finite volume of the exciton in phase space corresponds to the exciton size and can be directly measured by femtosecond pump-probe spectroscopy and by using the Phase Space Filling model for analysis. Our experiments result in a surprisingly large exciton size compared to earlier experimental and theoretical publications. We discuss possible reasons for this discrepancy.