Plasmonic Properties of Bimetal Nanoshell Cylinders and Spheres

K. Ehrhold[1], S. Christiansen[1,2], and U. Gösele[1]
[1]Max Planck Institute of Microstructure Physics, Halle, Germany,
[2]Institute of Photonic Technology, Jena, Germany

Plasmonics is a new branch of the fascinating field of photonics and develops concepts to quench light beyond the diffraction limit and enhance electromagnetic fields. These enhancements occur in metals as localized surface plasmon polaritons (LSP) a coupling of the surface density oscillations of the electron gas to the incident light. With threedimensional nano-structures of coinage metals that are brought in intimate contact with analytes of interest such as molecules one can utilize the locally enhanced electromagnetic field to excite characteristic vibration almodes. This enhanced Ramaneect gives the possibility to create spectroscopic vehicles which can act as highly sensitive molecular detector using Raman signals as a fingerprint of the analyte. The ectivity of the metal nanostructures for local field enhancement strongly depends on the geometry of the nanoparticle and its orientation with respect to the incident exciting laser light.

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