Our research focusses mainly on nanoparticles and nanostructured systems, the different research topics are connected by colloid chemistry and optics. Our activity ranges from designing and synthesizing new nanoparticle building blocks, to programmed and directed assembly of nanoparticles and characterization of their functional properties. For details, please refer to the Publication page.Andras Deak (PhD)
- Chemistry lab: Standard chemistry lab that allows state-of-the art aqueos synthesis of nanoparticles, Langmuir-Blodgett instrument (KSV2000) + Brewster Angle Microscope.
- Optics lab: Single particle spectroscopy (PI Isoplane 320 + PIXIS 400:BRX + Olypmus BX51 + Physik Instrumente Piezo stage), dyamic light scattering (Malvern NanoZS), conventional spectroscopy techniques and custom built setups (cryo-measurements, lock-in techniquest, etc.).
- Direct access to SEM.
- Numerical methods:
Matlab, Comsol (+ Labview)
- Other techniques accessible at our institute (TEM, clean-room, Raman, different SPM techniques, ellipsometry, etc.).
Main research areas:
CORE/SHELL AND Patchy nanoparticles
We develop high-quality core/shell and patchy nanoparticles that feature chemical or structural patchiness at the nanoscale. The aim is to create well-defined building blocks for the programmed and directed assembly of nanoscale objects. We utilize both bulk and interface processes to achieve patchiness. The bulk procedure relies on the different ligand coverage of highly curved surfaces (i.e. tips of gold nanorods), so that ligand molecules in this region can be selectively replaced. The interfacial approach builds on the partial exposure of the nanoparticle surface due to the masking effect of an interfacial layer. In practice this is achieved by partially immersing the nanoparticles into a polymer layer before the chemical modification (ligand replacement, material deposition) is carried at the exposed part of the particles.
Assembly of nanoparticles
Our aim is to gain insight into the assembly process by carrying out experiments at the ensemble and at the “single particle” level. The structure of the particle assemblies can be controlled by fine-tuning colloidal interactions. For the experiments nanoparticles with homogeneous or patchy nanoparticles are being used as well. Spherical particles are used for the preparation of companct nanoparticle clusters, while particles featuring shape-anisometry are epmloyed for site-specific localization of assembling particles.
We are engaged in single particle scattering spectroscopy to study the structure related optical properties of heterogeneous (Janus) particles and few particle assemblies. We rely on the enhanced scattering cross-section from gold nanoparticles to record their spectrum. Optical simulations and correlated scanning electron microscopy measurements allow a more fundamental insight into the assembly structure – optical properties relationship and provides feedback for the nanoparticle design and assembly control.
Interfacial templating using nanoparticles
The Langmuir-Blodgett technique allows the preparation of large area micro and nanoparticle monolayers on virtually arbitrary substrates. These layers can be used as a template to create interfacial nanostructures with special optical or structural properties. Approaches include large area nanowire growth, nanostructured plasmonic surfaces or capillary lithography.