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Since I've been a postdoc at Duke, my main focus has been on studying interactions between gold nanoparticles (NPs) and gold film. This has been a collaborative project with David Smith's group. We have shown that the plasmonic responses from film-coupled NPs are conceptually similar to those of plasmonically coupled NP dimers, and as such, film-coupled NPs undergo drastic color shifts in their localized surface plasmon resonances as the NP-film gap distance changes. In contrast to dimers, however, the presence of the film in the NP-film system polarizes the far-field light scattering of NPs situated nearby in a distance-dependent manner. Both the spectral and polarization responses from film-coupled NPs can be used as extremely sensitive and localized sensors of distance between the NPs and the nearby film. Additionally, nanoscale gaps created between NPs and film represent tightly confined ‘hot spots’ where electromagnetic fields are enhanced by many orders of magnitude. We have shown that these hot spots can be used to stimulate such low-probability events as surface enhanced resonant Raman scattering from molecules located within the gap regions between NPs and film. Thus, the NP-film system shares many of the sensing characteristics of coupled NP dimers, however, placing NPs on film to create plasmonically coupled systems is perhaps simpler than creating NP-NP dimers. Also, use of the metal film opens up the possibility of using surface chemistry and microfluidics to create chip-based plasmonically coupled sensors.


Recent Posters:

2012 Biointerface GRC/GRS, Switzerland

Biological Surfaces and Interfaces ESF-EMBO Symposium, Sant Feliu de Guixols, Spain; Triangle Soft Matter Workshop, UNC-CH

2010 Biointerface GRC, Switzerland