Karsten Kömpe

Synthesis of bifunctional Au/Pt/Au Core/shell nanoraspberries for in situ SERS monitoring of platinum-catalyzed reactions.

The synthesis of bifunctional Au/Pt/Au nanoraspberries for use in quantitative in situ monitoring of platinum-catalyzed reactions by surface-enhanced Raman scattering (SERS) is presented. Highly convolved SERS spectra of reaction mixtures can be decomposed into the contributions of distinct molecular species by multivariate data analysis.

3D self-assembled plasmonic superstructures of gold nanospheres: synthesis and characterization at the single-particle level.

The synthesis of 3D self-assembled plasmonic superstructures of gold nanospheres as well as the characterization of their structural and optical properties at the single-particle level is presented. This experimental work is complemented by FEM (finite element method) simulations of elastic scattering spectra and the spatial |E|(4) distribution for establishing structure-activity correlations in these complex 3D nanoclusters.

Multiplexing with SERS labels using mixed SAMs of Raman reporter molecules

Surface-enhanced Raman scattering (SERS) offers a tremendous multiplexing capacity for the selective detection of biomolecules in targeted research. SERS labels comprising self-assembled monolayers (SAMs) of Raman reporter molecules on the surface of metal nanoparticles are sensitive and robust probes. Advantages of a SAM include maximum sensitivity, minimal unwanted co-adsorption of molecules from the surroundings, and reproducible SERS spectra with only few dominant Raman bands—all of these independent of a particular SERS substrate. We demonstrate experimentally how to increase the multiplexing capacity of SERS labels by using mixed SAMs with up to three different Raman reporter molecules on the surface of the metal colloid. Type and stoichiometry of a particular Raman label in a multi-component SAM are additional parameters compared with one-component SAMs. All one-, two-, and three-component SAMs on gold nanospheres can be easily discriminated, either by their original SERS spectra or the corresponding bar codes.

Synthesis of β-Phase NaYF4:Yb,Er UpconversionNanocrystals and Nanorods by Hot-Injection of Small Particles of the α-Phase

Abstract β-NaYF4:Yb,Er upconversion nanocrystals are synthesized by a hot-injection method employing purified α-NaYF4:Yb,Er particles with a size of approximately 2–3 nm as single-source precursor. The method allows to prepare either spherical nanoparticles with different sizes or nanorods by simply controlling the addition rate of the solution of α-phase particles and performing the synthesis either in the absence or in the presence of seed particles. The luminescence properties of the different particles are compared also including core-shell particles.