Colloidal Metal Nanocrystals for Nanoplasmonics

Jianfang Wang

Department of Physics, The Chinese University of Hong Kong, Shatin,

Hong Kong SAR

In this presentation, I will describe the synthesis of colloidal gold nanocrystals and discuss their plasmonic properties and applications. I will mainly describe the syntheses of gold nanospheres, nanorods, nanobipyramids as well as silver nanorods. Their syntheses are all based on seed-mediated growth. Fine size tuning is realized through mild oxidation and anisotropic overgrowth, which allows for precise control of the plasmon resonance energies. All of the metal nanocrystals have very narrow size distributions. Their sizes and therefore their localized plasmon energies can be readily varied over broad spectral ranges by carefully controlling the synthetic conditions. I will then present the attractive plasmonic features of these noble metal nanocrystals, including their tunable plasmon wavelengths over a wide spectral range, extremely large absorption/scattering cross-sections, and large enhancements of local electric fields and densities of photonic states. Finally I will describe plasmonic applications out of our metal nanocrystals. Examples will include active plasmon switching, plasmonic catalysis, plasmonic sensing, time-temperature indicators and local photothermal heating.