Abstract Submitted to the    NANOTUBE'06 Conference:

Near-field optical imaging of single-walled carbon nanotubes

Achim Hartschuh ¹, Huihong Qian ², Tobias Gokus ², Alfred J Meixner ², Neil Anderson ³, Lukas Novotny ³

¹ LMU Muenchen, Germany
² University of Tuebingen, Germany
³ University of Rochester, USA

achim.hartschuh@uni-tuebingen.de

V. Other Characterization of Nanotubes

Photoluminescence and Raman spectroscopy are powerful tools for studying the electronic and vibronic properties of single-walled carbon nanotubes (SWNTs). Experiments on individual SWNTs, in particular, remove ensemble averaging involving different nanotube chiralities and can help to refine our understanding of nanotube physics. The spatial resolution achieved in conventional microscopy, on the other hand, is limited by diffraction to about half the wavelength of the excitation light. Thus, the spectroscopic data obtained results from spatial averaging over ~300 nm along the investigated nanotube.

Near-field optical techniques surpass the diffraction limit and can provide new insights into material properties on the nanometer scale. The technique we use is based on the local field enhancement at a laser-illuminated metal tip that acts as a highly confined excitation source. We present simultaneous photoluminescence and Raman spectroscopy of SWNTs with a resolution of about 10 nm [1,2]. We visualize the spatial extent of electronic states and probe emission energies along individual nanotubes [3]. For different sample materials, we observe a varying degree of localization of photoluminescence indicating the presence of bound excited states. Our results will help to clarify the influence of the local dielectric environment and of structural defects on the emission properties of SWNTs.

[1] A. Hartschuh et al., Phys. Rev. Lett. 90, 095503 (2003).
[2] N. Anderson et al., J. Am. Chem. Soc. 127, 2533 (2005).
[3] A. Hartschuh et al., Nano Lett. 5, 2310 (2005).

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