1. Institute of Nanotechnology, Karlsruhe Institute of Technology, H.-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
2. Karlsruhe Nano Micro Facility (KNMF), Karlsruhe Institute of Technology, H.-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
3. Regional Centre of Advanced Technologies and Materials Department of Physical Chemistry, Faculty of Science, Palacky University, Šlechtitelů 27, 78371 Olomouc, Czech Republic
4. Institute of Physical Chemistry, Karlsruhe Institute of Technology, Fritz-Haber Weg 2, G 30.44, 76131 Karlsruhe, Germany
5. Institut de Physique et Chimie des Matériaux de Strasbourg, CNRS-Université de Strasbourg, 23 Rue du Loess, BP 43, Strasbourg CEDEX 2 67034, France