Title：Plasmon Enhanced Nonlinear Optical Properties and Their Applications

Speaker：Qing-Hua Xu (徐清华)

                Department of Chemistry, National University of Singapore

Time：10:00-11:00am, June 11, 2019

Location：701-B501, Dushu Lake Campus

Abstract: Noble metal nanoparticles (NPs), such as gold (Au) and silver (Ag), display unique properties known as localized surface Plasmon resonance, which could be utilized to enhance linear and nonlinear optical properties of nearby chromophores and metal nanoparticles themselves. In this talk, I will present our group’s efforts on various plasmon enhanced optical properties and their applications. In particular, our group found an interesting phenomenon that two-photon photoluminescence (2PPL) of metal NPs were significantly enhanced upon formation of aggregates, up to >800-fold in the colloid solution and several orders of magnitude on single particle level. This phenomenon has been further utilized to develop various two-photon sensing and imaging applications. The underlying enhancement mechanisms have been investigated by using ultrafast spectroscopy and single particle spectroscopy. Furthermore, photothermal responses of aggregated metal NPs in the near-Infrared region were also found significantly enhanced, which render them dual-capability of photothermal imaging and treatment of human prostate cancer cells with high efficiency and selectivity.

About the speaker: XU Qing-Hua (徐清华) received his B.S. from Zhejiang University (1993), M.S. from Peking University (1996) and University of Chicago (1997), Ph.D. from UC Berkeley (2001), and conducted the postdoctoral research at Stanford University and UC Santa Barbara. He joined NUS Chemistry in 2005 and became a tenured associate Professor since 2011. His primary research interest is development of various light based applications such as sensing, imaging, photosensitization and optoelectronics using various low-dimension materials, as well as investigation of the underlying fundamental mechanisms using various novel optical spectroscopy and imaging techniques. So far he has published ~200 peer reviewed articles with citations of >9000 times and H-index of 57.