1. Institute for Applied and Physical Chemistry (IAPC), University of Bremen, Fachbereich 2 (Chemie/Biologie), Leobener Straße / NW 2, Postfach 330440, D-28334 Bremen, Germany
2. Christian Doppler Laboratory for Direct-Write Fabrication of 3D Nano-Probes (DEFINE), Institute of Electron Microscopy and Nanoanalysis, Graz University of Technology, Steyrergasse 17, A-8010 Graz, Austria
3. Institute of Electron Microscopy and Nanoanalysis, Graz University of Technology, Steyrergasse 17, A-8010 Graz, Austria
4. Graz Centre for Electron Microscopy, Steyrergasse 17, A-8010 Graz, Austria