Regensburg 2010 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 59: Poster Session II (Nanostructures at surfaces: Dots, particles, clusters; Nanostructures at surfaces: arrays; Nanostructures at surfaces: Wires, tubes; Nanostructures at surfaces: Other; Plasmonics and nanooptics; Metal substrates: Epitaxy and growth; Metal substrates: Solid-liquid interfaces; Metal substrates: Adsoprtion of organic / bio molecules; Metal substrates: Adsoprtion of inorganic molecules; Metal substrates: Adsoprtion of O and/or H; Metal substrates: Clean surfaces; Density functional theory and beyond for real materials)

O 59.43: Poster

Mittwoch, 24. März 2010, 17:45–20:30, Poster B1

Probing Exciton Propagation and Localization in Single-Walled Carbon Nanotubes — •Carsten Georgi, Miriam Böhmler, and Achim Hartschuh — Department Chemie und Biochemie & CeNS, Ludwig-Maximilians-Universität München, Germany

Tip-enhanced near-field photoluminescence (PL) microscopy providing nanoscale spatial resolution has been mainly used to image localized emitters, such as single molecules [1,2]. Semiconducting single-walled carbon nanotubes are photoluminescent 1D-nanostructures with highly mobile excited states (excitons). We study exciton propagation by combining near-field PL measurements and numerical simulations describing exciton diffusion and the imaging process. Hereby, we can extract e.g. the exciton diffusion range [3]. In some cases, highly confined and exceptionally bright PL is observed and attributed to exciton localization. This localization results from strong exciton energy gradients exceeding 2 meV/nm, evidenced by energy-resolved PL imaging. Numerical simulations of exciton diffusion in the presence of energy variations support this interpretation predicting strongly enhanced PL at local energy minima. Our results indicate that the PL intensity along a single nanotube is determined by the complex interplay between exciton mobility, localization and quenching sites.

[1] A. Hartschuh, Angew. Chem. Int. Ed. 47, 8178 (2008)

[2] T. Taminiau et al., Nature Photon. 2, 234 (2008)

[3] C. Georgi et al., phys. stat. sol. (b) 246, 2683 (2009)