Journal Title
Title of Journal: BioNanoSci
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Abbravation: BioNanoScience
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Authors: JeanClaude Tinguely Idrissa Sow Claude Leiner Johan Grand Andreas Hohenau Nordin Felidj Jean Aubard Joachim R Krenn
Publish Date: 2011/09/13
Volume: 1, Issue: 4, Pages: 128-135
Abstract
Noble metal nanoparticles show specific optical properties due to the excitation of localized surface plasmons that make them attractive candidates for highly sensitive bionanosensors The underlying physical principle is either an analyteinduced modification of the dielectric properties of the medium surrounding the nanoparticle or an increase of the excitation and emission rates of an optically active analyte by the resonantly enhanced plasmon field Either way besides the nanoparticle geometry the dielectric properties of the metal and nanoscale surface roughness play an important role for the sensing performance As the underlying principles are however not yet well understood we aim here at an improved understanding by analyzing the optical characteristics of lithographically fabricated nanoparticles with different crystallinity and roughness parameters We vary these parameters by thermal annealing and apply a thin gold film as a model system to retrieve modifications in the dielectric function We investigate on one hand extinction spectra that reflect the farfield properties of the plasmonic excitation and on the other hand surfaceenhanced Raman spectra that serve as a nearfield probe Our results provide improved insight into localized surface plasmons and their application in bionanosensingThe authors would like to thank Georg Jakopic of the Joanneum Research Institute in Weiz for the ellipsometry measurements This work has been supported in part by the Austrian Fonds zur Förderung der wissenschaftlichen Förderung FWF under project no 21235N20
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