Plasmonic properties of monolayers of strongly interacting silver nanocubes (AgNC) with controlled interparticle spacing are investigated. Uniform monolayers with controlled particle densities are made using the Langmuir-Blodgett technique with passive phospholipid spacers, such as dioleoyl phosphatidylcholine (DOPC). Both extinction intensity and wavelength of dipole-dipole coupling modes are tuned via particle spacing. The refractive indices of the substrates are used to tune dipolar and interparticle coupling modes via deposition onto thin films of silicon (0 - 25nm). By varying silicon film thickness it is possible to shift and control peak widths and position for both the dipole and interparticle dipole-dipole coupling modes. Control of plasmon shifts and interparticle spacing is applied towards the optimization of SERS substrates. SERS substrates using a Rhodamine B label are tuned at different excitation wavelengths which are in resonance with either the plasmon dipole, fluorescent dye, or interparticle coupling mode. Substrates display reproducible enhancement across multiple sites. This work presents methodology to design and optimize uniform silver nanocube SERS substrates through tuning of plasmon shifts and particle spacing.

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Keywords Langmuir-Blodgett, Nanocrystal, nanocube, plasmon coupling, plasmon tuning, SERS
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Conference Plasmonics in Biology and Medicine X
Prezgot, D. (Daniel), & Ianoul, A.I. (2013). Optical properties of strongly interacting supported silver nanocube monolayers. Presented at the Plasmonics in Biology and Medicine X. doi:10.1117/12.2002568