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Institutskolloquium der Physik und Chemie: "Brilliant Infrared Spectroscopic Polarimetry of Thin Films and Surfaces"

Die Hochschullehrer der Institute für Physik und Chemie der TU Ilmenau laden am Dienstag, dem 4. Februar 2020, zu einem gemeinsamen Kolloquium der Physik und Chemie ein.

Es spricht um 17:15 Uhr im Faraday-Hörsaal PD Dr. Karsten Hinrichs vom Leibnitz-Institut für Analytische Wissenschaften e. V. (ISAS) Berlin zum Thema "Brilliant Infrared Spectroscopic Polarimetry of Thin Films and Surfaces".

Zum Vortrag:

Infrared (IR) spectroscopic techniques in linear optics are often mainly seen only as tools for identifying functional groups of molecules analyzing characteristic molecular vibrations via specific absorption bands. However, combining the measurements with optical simulations enables for an in-depths characterization of various sample parameters. In the case of structured surfaces, thin films or anisotropic materials typically more elaborated polarization dependent IR spectroscopic analysis is required for reliable determination of spectra-structure correlations. A combination of analytical and numerical calculations can be applied in such cases for a comprehensive interpretation.

In this talk I will focus on IR polarimetric investigations for studies of anisotropic, structured or depolarizingsurfaces and thin films. Some recent results from investigations of molecular aggregates, thin polymer and oxide films will be discussed. For such studies, in particular the availability of mid-IR quantum cascade lasers (QCL) significantly broadened the number of applications allowing for investigations from macroscopic to nanoscopic length scales. We recently combined a QCL with a scheme for the single shot detection of different polarization states in an ellipsometric measurement routine. This development opens up the door to new experimental possibilities for sensitive thin film studies with high time resolutions in the μs to ms range combined with high spectral (< 0.5 cm-1) and lateral resolutions (< 250 μm). For polarimetric studies at the nanoscale the photothermal AFM-IR technique equipped with a tunable QCL and a polarizing unit was used. These polarimetric possibilities can be of high interest in a wide field of applications as anisotropy and structure are essential for physical, chemical and functional properties of a plethora of materials in optoelectronic, polymer, plasmonic, and bio-related research. Currently in our group at ISAS-Berlin we are working on combining the laser ellipsometry set-up for analysis of processes at solid-liquid interfaces in questions related to non-cyclic processes or sensing interactions in microfluidic flow cells.