Lecture Manfred Matena
|18 October 2012||FWN-Building 5118.-152, Nijenborgh 4, 9747 AG, Groningen|
|Speaker:||Dr. Manfred Matena|
|Affiliation:||Universität Duisburg – Essen, Germany|
|Title:||Altering the band structure: The interplay between ordered ad-layers and the substrate|
|Date:||Thu Oct 18, 2012|
|Telephone:||+31 50 363 4438|
Electronic states in metal crystals may be significantly altered when the surface is periodically textured, e.g. with molecules, adatoms or dislocations. Angle resolved photoelectron spectroscopy (ARPES) is a suitable technique to study such systems because it allows for a direct measurement of the dispersion of electronic bands. The triangular dislocation network observed for Ag/Cu(111) is a particularly attractive case for changes induced by the surface texture because it opens a gap in the parabola of the free-electron-like surface state. The first part of this talk will show how the band structure of this system can be tuned by the addition of Au atoms at the Cu interface. This "Au-doping" shifts down the band structure, so that the band gap moves entirely across the Fermi energy.
The second part of the talk will deal with the perylene derivative TAPP, which forms one-dimensional chains of covalently bonded molecules on Cu(111) upon annealing. This transition from isolated to covalently linked molecules is expected to be accompanied by changes in the electronic structure of the system, e.g. the now delocalized molecular orbitals of these chains may form dispersive electronic bands. In order to make this system accessible to the laterally averaging technique ARPES, ordered ad-layers with well-defined symmetries are needed. Thus, in this case a stepped surface is used to align the chains along a single direction.
|Last modified:||22 October 2012 2.30 p.m.|