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Plasmon Enhanced Nonlinear Optical Properties for Biomedical Applications

Xu Qing-Hua (Department of Chemistry, NUS)
Wed, 15/04/2015 - 11:00am to 12:00pm
Physics Conference Room (S13-M01-11)
Event Type: 


Noble metal nanoparticles, such as gold and silver, 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. Our group has done extensive work on plasmon enhanced one- and two-photon excitation fluorescence and their applications. In particular, we found an interesting phenomenon that non-fluorescence metal nanoparticles started to emit strong two-photon photoluminescence (TPPL) upon plasmon coupling in the aggregated state. We have demonstrated that this kind of plasmon coupling enhanced TPPL is a general phenomenon for Au and Ag nanoparticles of different morphologies. TPPL of these metal nanoparticles was found to be enhanced by up to hundreds of times in the colloid solution and five orders of magnitude on single particle level upon plasmon coupling. As many biologically important species can induce aggregation of metal nanoparticles, this phenomenon has been further utilized to develop various two-photon sensing and imaging applications to take their unique advantages of deep penetration into biological tissues and 3-dimensional confined excitation. We have also employed ultrafast spectroscopy techniques to understand the underlying enhancement mechanisms.

About the speaker

XU Qing-Hua 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 an Associate Professor since 2011. His primary research interest is development of various light based applications such as sensing, imaging, photosensitization and optoelectronics using various nanomaterials and organic/polymer materials, as well as investigation of the underlying fundamental mechanisms using various novel optical spectroscopy and imaging techniques. For more information about the research in his research group, please visit the group's home page here.

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