Regensburg 2013 – scientific programme

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O: Fachverband Oberflächenphysik

O 43: Plasmonics and Nanooptics IV

O 43.11: Talk

Wednesday, March 13, 2013, 13:00–13:15, H31

Raman spectra of individual carbon nanotubes manipulated by surface plasmons — •Nicola Paradiso, Fatemeh Yaghobian, Tobias Korn, Christian Schüller, and Christoph Strunk — Institut für Experimentelle und Angewandte Physik, Universität Regensburg.

The Raman spectrum of individual carbon nanotubes (CNTs) can be enhanced by noble metal nanoparticles, due to surface-enhanced Raman scattering (SERS). In this work we exploit lithographically patterned nanoparticles to locally obtain SERS from the desired position along a CNT. Such structures consist of arrays of sharp triangular metal pads separated by a 20 nm-wide gap, which are fabricated via electron beam lithography. AFM scans allow us to align the lithography so that the CNT is lying within the gap between two nanostructures. When illuminated with the Raman source, surface-plasmons are generated at the surface of these gap sized engineered structures. This method allows us to separately characterize electromagnetic and the chemical contributions in SERS. In particular, we have analyzed how the presence of noble metal structures manipulates the radial breath mode in the spectrum, and how the G+/G- amplitude ratio is locally modified. Such an ``on-chip" optical interface will make it possible to manipulate the optical features of the CNTs and allow to directly assigning the chirality of given individual CNTs.