Surface Science and Infrared Spectroscopy of Nanostructures
Our research focuses on nanostructures (ultrathin layers and nanoparticles from atomic size up to several 100 nm on well-defined surfaces) with emphasis on the relationship between structure formation, surface, and interface properties and excitation spectra in the infrared (IR) range. Surface and interface properties become increasingly important with the decreasing size of nanostructures.
In the last decade we have explored the coupling between plasmonic and vibrational excitations in the infrared spectral range. This Fano-type coupling produces up to a million times amplified vibrational signals enhanced vibrational signatures, known as the surface enhanced IR absorption (SEIRA) with resonant plasmonic enhancement. IR plasmonic resonances of many nanometer-thick and also of only a few atoms thin linear nanostructures have been analyzed also in terms of their electronic conductivity, which provides information on the electronic band structure at the Fermi level and on electronic scattering.
Our main experimental tools are IR spectroscopy (including IR micro-spectroscopy, IR spectroscopic ellipsometry) under ambient and ultra-high vacuum conditions at various temperatures. Studies have been performed within a variety of research projects ranging from astronomy and high-energy physics to plasmonics and organic electronics. Materials in organic electronics show rich vibrational fingerprint spectra that are unique for a molecular species in a certain environment. For this reason, IR spectral characterization becomes a powerful tool for the study of changes in the geometric and electronic structure of organic semiconductors.