1. Institute of Applied Physics and Center for Functional Nanostructures (CFN); Karlsruhe Institute of Technology (KIT); 76131 Karlsruhe Germany
2. Laboratory of Electron Microscopy; Karlsruhe Institute of Technology (KIT); 76131 Karlsruhe Germany
3. Institute of Functional Interfaces; Karlsruhe Institute of Technology (KIT); 76344 Eggenstein-Leopoldshafen Germany
4. Institute of Toxicology and Genetics; Karlsruhe Institute of Technology (KIT); 76344 Eggenstein-Leopoldshafen Germany
5. Department of Physics; University of Illinois at Urbana-Champaign; Urbana IL 61801 USA