Institute of Physical and Theoretical Chemistry

Research topics

Developing multifunctional microscopic technique

 

We develop new multifunctional microscopic techniques based on Raman, and fluorescence signals, such as tip-enhanced optical spectroscopy and microscopy. Based on the ‘localized plasmon effect’ and the ‘lightning effect’, an optically excited sharp noble metal tip raster scans over the sample surface at a very close tip-sample distance (e.g. less than 3 nm), allowing to collect the topography and optical information at the nanometer scale simultaneously. This combination provides a unique view-point to investigate nanoscale physical and chemical properties.

Ongoing projects:

Probing the nanoscale properties of two-dimensional van der Waals heterostructures by tipenhanced nano-imaging and spectroscopy (Humboldt Research Fellowship, 2021-2023)

The investigation of local properties of optoelectronic materials at the nanometer scale using optical spectroscopy and microscopy (CSC, 2022-2025)

Collaboration. Dr. J. Y. Wang, Westlake University, P. R. China

Optical/electrical properties of organic semiconductors and the hybrid systems

We investigate organic semiconductor systems that are commonly used in photovoltaics and organic light emitting diode and their hybrids with metallic nanostructures. We are particularly interested in studying the morphology – related issues, such as the molecular stacking orders, orientation, and the domain formation (size and the arrangement). These issues are found to be critical in the light-management, the charge carrier mobility, exciton diffusion and dissociation in many optoelectronic devices. Employing the unique scanning near-field optical microscopy developed in our lab, we are able to direct study these effects at both micro- and nanometer scale.

Collaborators:

Prof. H. Peisert (Chemistry), Prof. T. Chassé (Chemistry), Prof. F. Schreiber (Physics), Uni. Tübingen, Germany

Prof. C. Brabec, Department of Materials Science and Engineering, Friedrich Alexander University Erlangen Nürnberg, Germany

Prof. J. Gierschner, IMDEA Nanoscience Madrid, Spain

Optical properties of metallic plasmonic nanostructures

We investigate metallic nanostructures of different composition and geometry, especially regarding the plasmonic resonance influences on the second harmonic generation, two/one photon photoluminescence, and surface-enhanced Raman scattering.

Collaborators:

Prof. M. Fleischer (Physics), Uni Tübingen, Germany

Prof. P. M. Adam, Prof. Anne-Laure Baudrion-Béal, Laboratoire Lumière, nanomatériaux, nanotechnologies (L2n), Université de Technologie de Troyes, France

Prof. O. J. F. Martin, École Polytechnique Fédérale de Lausanne, Switzerland

 

Fluorescence microscopy and lifetime imaging in dry and liquid conditions

We investigate the optical properties (Raman and fluorescence) of molecules, soft matters, and thin films in dry and liquid conditions. Through the non-linear effects, optical imaging with intrinsic confocal optical resolution in three-dimensional can be achieved.

Collaborators:

Dr. A. Lorenz, Prof. M. Brecht, Reutlingen University, Germany