Dresden 2014 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 46: Plasmonics and Nanooptics I

O 46.1: Vortrag

Mittwoch, 2. April 2014, 10:30–10:45, TRE Phy

Tailored nano-antennas for directional Raman studies of individual carbon nanotubes — •Nicola Paradiso, Fatemeh Yaghobian, Christoph Lange, Tobias Korn, Christian Schüller, Ruper Huber, and Christoph Strunk — Institut für Experimentelle und Angewandte Physik, University of Regensburg

We exploit patterned nano-antennas to investigate the Raman spectra of otherwise not optically detectable carbon nanotubes (CNTs). We demonstrate that a top–down approach is particularly promising when applied to CNTs, owing to the sharp dependence of the scattered signal on the angle between incident light polarization and CNT axis. In contrast to tip enhancement techniques, our method enables us to control the light polarization in the sample plane, locally amplifying and rotating the incident field in order to optimize the Raman signal. Such promising features are confirmed also by the numerical simulations presented here. From the analysis of the G modes we deduced that the CNT under study is semiconducting and chiral, and we estimated its diameter and chiral angle. Measurements on arrays with different orientation with respect to the CNT revealed that thin metal strips allow not only to magnify, but also to rotate the electromagnetic field, thus introducing a new degree of freedom for SERS applications. The relative ease of fabrication and alignment makes this technique suitable for the realization of integrated devices that combine scanning probe, optical, and transport characterization.