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Calendar of Physics Talks Vienna
| On the energy to switch an individual molecule: scrutinizing dynamic processes of porphyrins on surfaces close to room temperature |
| Speaker: | Ph Dr. Hubertus Marbach (Microscopy and Nanolithography Group, PC II, Universität Erlangen-Nürnberg/Germany) |
| Abstract: | Scanning tunneling microscopy (STM) enables to directly observe the dynamic behavior of organic molecules on surfaces. While imaging atoms and molecules in STM is certainly fascinating by itself, corresponding temperature-dependent measurements allow for the quantitative determination of the energetics and kinetics of the underlying molecular surface processes. Free-base porphyrins on Cu(111) proved to be particularly suitable for these studies due to the strong bonding interaction between the iminic nitrogen atoms in the porphyrin macrocycle with the Cu substrate atoms. As a consequence, the corresponding activation energies for surface diffusion, self-metalation reaction and conformational switching are of a magnitude that allows for monitoring the processes around room temperature, in contrast to most previous studies, which were performed at cryogenic temperatures. The Arrhenius type |
| Date: | Tue, 05.07.2016 |
| Time: | 16:00 |
| Location: | Technische Universität Wien, Institut für Angewandte Physik, E134 yellow tower „B“, 5th floor, Sem.R. DB gelb 05 B (room number DB05L03) 1040 Wien, Wiedner Hauptstraße 8-10 |
| Contact: | Univ.Prof. Dr. Ulrike Diebold |
| Spin-orbit coupling of light for polarization controlled nano-optics |
| Speaker: | Francisco Rodríguez Fortuño (King's College London ) |
| Abstract: | Spin-orbit coupling of light describes how spin angular momentum of light (associated with circular/elliptical polarization of the electric field) is coupled to orbital angular momentum of light (associated with the energy flow and propagation direction). I will focus on a specific example of "spin orbit coupling" related to electromagnetic evanescent waves: the polarization of such waves is elliptically polarized, with a spin that is directed transverse to the propagation direction, and the sense of rotation of the polarization is directly related to the direction of propagation of the wave - this allows controlling the propagation direction simply by tuning the polarization of a localized source. This effect is very fundamental, broadband, and robust to imperfections. I will give an alternative interpretation of the effect from the point of the unidirectional character of the near fields of the dipole itself, and I will describe different experiments which we carried out to test this effect and its reciprocal version |
| Date: | Fri, 08.07.2016 |
| Time: | 15:30 |
| Location: | Atominstitut, Hörsaal, Stadionallee 2, Wien 2 |
| Contact: | P. Schneeweiß |
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