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Plasmonics deals with the study of optical resonances supported by metallic
nanostructures and thin films. Plasmonic nanostructures have been used for the
development of ultrasensitive sensing platforms that can detect even single
molecules. Conventionally, noble metals like gold, silver and copper have been used
for making the nanostructures supporting strong plasmon resonances. More
recently, there has been significant attention paid to alloy plasmonics due to their
increased tunability. In this talk, I will demonstrate two different aspects of alloy
plasmonics using the Ag-Cu alloy system. In the first part of the talk, I will talk about
propagating surface plasmons supported by Ag-Cu alloy thin films. The effect of
composition and microstructure on the surface plasmon behavior will be elucidated
using both experimental and numerical tools. Experimentally, such complex alloy thin
films were fabricated using magnetron co-sputtering process followed by vacuum
annealing. In the second part of the talk, I will look at the localized plasmons
supported by Ag-Cu nanoparticles. The effect of various geometrical parameters on
the plasmon resonance as well as the Raman enhancement for a given laser
wavelength will be demonstrated. It will be shown that these two-phase particles
exhibit dual resonances which can be exploited for realizing SERS based
biosensors. |