ABSTRACT
Research Institute for Electron Microscopy, Graz University of Technology, Steyrerg. 17, A-8010 Graz, Austria; *>Institute for Solid State Physics, Graz University of Technology, Petersgasse 16111, A-8010 Graz, Austria; **>Borealis GmbH, St. Peter Str. 25, A-4021 Linz, Austria.
