Abstract: Localized surface plasmon resonance brings noble metal nanostructures with many attractive optical properties. Three major ones are (i) synthetically tunable plasmon resonance wavelengths, (ii) enhanced absorption and scattering cross-sections, and (iii) enhanced local electric fields and densities of photonic states. These properties have enabled potential applications of metal nanostructures in a wide range of areas, including bionanotechnology, nanomedicine, sensing, molecular spectroscopy, solar energy harvesting, linear and nonlinear optics and optoelectronics. In this presentation, I will mainly talk about plasmon-controlled fluorescence and plasmon coupling. Plasmon can not only amplify the fluorescence emission intensity of adjacent organic molecules, but also change their emission energy and polarization. Plasmon coupling can cause much larger local electric field enhancements, dramatic changes in plasmon resonance modes, as well as many interesting optical phenomena. We have been studying and trying to understand the dependence of plasmon coupling on the gap between neighboring metal nanocrystals, their relative orientation, plasmon energies and positions. Our gained understanding in plasmon coupling will be very useful for designing and fabricating complex assemblies, hierarchical structures, and macroscopic materials out of noble metal nanocrystal building blocks, much similar to the formation of molecules and macroscopic materials out of atoms, with desired plasmon-derived functions.
Jianfang Wang is currently an associate professor in the Department of Physics of The Chinese University of Hong Kong (CUHK). He obtained his bachelor's degree in inorganic chemistry and software design from University of Science and Technology of China (USTC) in 1993, his master's degree in inorganic chemistry from Peking University (PKU) in 1996, and his PhD degree in physical chemistry from Harvard University in 2002. He did postdoctoral studies in University of California, Santa Barbara from February 2002 to July 2005. His current research interests focus on metal nanocrystals, metal oxide nanostructures, and nanoplasmonics. More details about the research works in his group can be found at http://www.phy.cuhk.edu.hk/~jfwang/.