Controllable synthesis of Pd and Pt shells on Au nanoparticles with electrodeposition.

Shells of Pd and Pt were synthesized on Au nanoparticles by electrodeposition, leading to controllable size and optical properties. This approach yielded core-shell structures with good homogeneity in size after the optimization of electrochemical parameters such as deposition current and charge transfer, as well as nanoparticle surface treatment. Dark field scattering microscopy and spectroscopy were used to track changes in the optical response of individual particles during deposition.

Magnesium Nanoparticles for Surface-Enhanced Raman Scattering and Plasmon-Driven Catalysis.

Nanostructures of some metals can sustain localized surface plasmon resonances, collective oscillations of free electrons excited by incident light. This effect results in wavelength-dependent absorption and scattering, enhancement of the incident electric field at the metal surface, and generation of hot carriers as a decay product. The enhanced electric field can be utilized to amplify the spectroscopic signal in surface-enhanced Raman scattering (SERS), while hot carriers can be exploited for catalytic applications.

Plasmonic Properties of Self-Assembled Gold Nanocrescents: Implications for Chemical Sensing.

A bottom-up approach, the Langmuir-Blodgett technique, is used for the preparation of composite thin films of gold nanoparticles and polymers: poly(styrene--2-vinylpyridine), poly-2-vinylpyridine, and polystyrene. The self-assembly of poly(styrene--2-vinylpyridine) at the air-water interface leads to the formation of surface micelles, which serve as a template for the organization of gold nanoparticles into ring assemblies. By using poly-2-vinylpyridine in conjunction with low surface pressure, the distance between nanostructures can be increased, allowing for optical characterization of single nanostructures.

Far-field, near-field and photothermal response of plasmonic twinned magnesium nanostructures.

Magnesium nanoparticles offer an alternative plasmonic platform capable of resonances across the ultraviolet, visible and near-infrared. Crystalline magnesium nanoparticles display twinning on the (101̄1), (101̄2), (101̄3), and (112̄1) planes leading to concave folded shapes named tents, chairs, tacos, and kites, respectively. We use the Wulff-based Crystal Creator tool to expand the range of Mg crystal shapes with twinning over the known Mg twin planes, , (101̄), = 1, 2, 3 and (112̄), = 1, 2, 3, 4, and study the effects of relative facet expression on the resulting shapes.

Halide-assisted differential growth of chiral nanoparticles with threefold rotational symmetry.

Enriching the library of chiral plasmonic nanoparticles that can be chemically mass-produced will greatly facilitate the applications of chiral plasmonics in areas ranging from constructing optical metamaterials to sensing chiral molecules and activating immune cells. Here we report on a halide-assisted differential growth strategy that can direct the anisotropic growth of chiral Au nanoparticles with tunable sizes and diverse morphologies. Anisotropic Au nanodisks are employed as seeds to yield triskelion-shaped chiral nanoparticles with threefold rotational symmetry and high dissymmetry factors.