报告题目：Surface-enhanced Raman scattering spectroscopy: a versatile tool for probing plasmonic spatial nonlocality and monitoring chemical reaction dynamics
报 告人：Lei Dang Yuan教授 香港理工大学
Abstract: In the last decades, surface-enhanced Raman scattering (SERS) spectroscopy has become a versatile vibrational spectroscopic technique with a number of applications in the chemical, material and, in particular, life sciences. In the first part of this talk, I will show our recent work on the use of SERS spectroscopy for probing the spatial nonlocality effect, which is recently believed to set an ultimate limit of plasmonic near-field enhancement in metallic nanostructures with critical dimensions on the order of a few nanometers or less . I will present our theoretical and experimental investigations on the effect of spatial nonlocality in metal films with controllable surface roughness . In theory, we have used a well-established nonlocal hydrodynamic model to describe the collective motion of conduction electrons and calculate the near-field enhancement at the surface of silver films. In experiment, we have used the SERS spectroscopic technique to probe indirectly the near-field enhancement factor as a function of surface roughness by measuring the SERS intensity of conformally coated graphene monolayers on a series of silver films. Our results reveal that the spatial nonlocality effect of the metal dielectric response has to be taken into account for more accurate prediction of the SERS enhancement at large surface roughnesses. In the second part of this talk, I will show the use of SERS spectroscopy for monitoring catalytic reaction dynamics provided that plasmonic metal nanoparticles for Raman enhancement are properly integrated with catalytic metals to form a single entity. I will present a facile approach for synthesizing Au@Pt core/shell nanostructures with controllable surface density of sub-5 nm Pt nanoparticles on the surface of Au nanorods. Systematic investigations on both SERS and catalytic activities of the hybrid nanostructures reveal an optimized surface coverage of Pt. More importantly, due to their dual functionalities, the hybrid nanostructures are able to track the Pt-catalyzed reaction in real time by measuring the SERS signals of the reactant, intermediate and final products.
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Biography: Dang Yuan Lei received his BSc and MPhil degrees, both in Physics, from