Wenzhong Wang

Polarization Dependence of Surface-Enhanced Raman Scattering in Gold Nanoparticle-Nanowire Systems

We study the polarization dependence of surface-enhanced Raman scattering (SERS) in coupled gold nanoparticle-nanowire systems. The coupling between the continuous nanowire plasmons and the localized nanoparticle plasmons results in significant field enhancements and SERS enhancements comparable to those found in nanoparticle dimer junctions. The SERS intensity is maximal when the incident light is polarized across the particle and the wire, and the enhancement is remarkably insensitive to the detailed geometrical structures of the nanoparticles.

High-Yield Uniform Synthesis and Microstructure-Determination of Rice-Shaped Silver Nanocrystals

High-yield uniform silver nanorices were synthesized by a facile polyol process without the introduction of shape-selected seeds. Nanorices exhibit two plasmon resonance peaks in the visible and near-infrared regions respectively due to their anisotropy. XRD patterns demonstrated the HCP phase coexists with the FCC phase in nanorices. The novel structure of nanorices was characterized by TEM study which shows that the intergrowth of FCC and a small amount of HCP phase, nanoscale FCC (111) twinning structure, and multimodulated structures formed by a complicated stacking sequence along the long axis direction. The correlation between morphology and microstructure is discussed.

Enormous Surface‐Enhanced Raman Scattering from Dimers of Flower‐Like Silver Mesoparticles

The surface-enhanced Raman scattering (SERS) of flower-like silver mesoparticle dimers with large hot areas is ≈10 to 100 times higher than the individual mesoparticles. The dependence of incident polarization illustrates that, even in the rough-surface mesoparticle dimer system, the coupling effect still dominates the SERS. More importantly, the micro-manipulator can be used to form dimers controlled with high SERS quality.

Control light propagation and polarization with plasmons for surface-enhanced Raman scattering

Surface plasmon resonances in metal nanostructures can lead to novel optical properties. The greatly enhanced electromagnetic field makes surface-enhanced Raman scattering (SERS) a highly sensitive spectroscopic technique. We employed Ag nanowires as plasmonic waveguide and achieved remote-excitation SERS at a few molecules level. The junctions between metal nanowires and nanoparticles offer hot spots for SERS, while the enhancement strongly depends on the laser polarization. We studied the polarization dependence in Au nanowire-nanoparticle systems of different geometry. The polarization of Raman-scattered light in SERS is a rarely studied topic. We found nanoantennas composed of a few nanoparticles can manipulate the polarization of emission light. A nanoparticle trimer is the simplest nanoantenna to realize the polarization control. By tuning the position and size of the third particle, emission polarization can be modified in a controllable way. In addition, the refractivity of the surrounding media also plays a crucial role for the emission polarization.