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28.05.2019

Institutskolloquium der Physik und Chemie: Doktorandenseminar

Die Hochschullehrer der Institute für Physik und Chemie der TU Ilmenau laden am Dienstag, dem 28. Mai, im Rahmen des gemeinsamen Kolloquiums der Physik und Chemie zu einem Doktorandenseminar ein.

Doktoranden aus den Fachgebieten Experimentalphysik I, Theoretische Physik I sowie Angewandte Nanophysik stellen ab 17:15 Uhr im Faraday-Hörsaal ihre Ergebnisse vor.

Es sprechen

M. Sc. Jonathan Brand, Fachgebiet Experimentalphysik,

zum Thema:"Non-equilibrium bond forces in single-molecule junctions"

The combination of first principles calculations and force spectroscopy experiments unravel attractive current-induced forces in C60-C60 junctions. These forces result from the non-equilibrium population of intermolecular bonding and antibonding orbitals. They occur in the vicinity of chemical-bond distances, dominate electrostatic interactions due to accumulated charge density on the molecules and exhibit a nearly parabolic evolution with the bias voltage. Experimental data obtained from a combined atomic force and scanning tunnelling microscope using a C60-terminated tip and various C60 assemblies adsorbed on Cu(111) corroborate the theoretical findings.

M. Sc. Tobias Gäbler/PD Dr. Wichard Beenken, Fachgebiet Theoretische Physik I

zum Thema: "Reconstruction of Metastable Induced Electron Spectra of molecules on solid surfaces"

The Metastable Induced Electron Spectroscopy (MIES) allows an extremely sensitive electronical characterization of liquid and solid surfaces by deexcitation of metastable rare gas atoms. We present a quantum-chemical approach for ab initio calculations of MIES spectra of molecules physisorbed on solid surfaces. For this purpose, we calculate spatially distributed transition rates of the Auger deexcitation process without the simplifying assumptions as proposed by Kantorovich et al. [1]. Thereby, we model the density of metastable Helium atoms along a series of trajectories approaching the sample molecule. According to experimental results for benzene [2], our calculations demonstrate - in contrast to the approach of Kantorovich et al. [1] - an anisotropy of the MIES spectra in respect not only to the molecule orientation but also to the electron detection direction. Thus, due to the ajustable direction of the incidence of metastable helium and of the detection of emitted Auger-electrons in the simulation, our method is able to forecast MIES spectra for arbitrary experimental setups.

 

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