1. TU Braunschweig, Institute of Particle Technology Volkmaroder Str. 5, 38104 Braunschweig, Germany, Fax: +49‐531‐3919615
2. Max Planck Institute of Colloids and Interfaces, Research Campus Golm, 14424 Potsdam, Germany
3. TU Braunschweig, Institute of Condensed Matter Physics Mendelssohnstr. 3, 38106 Braunschweig, Germany
4. ETH Zurich, Department of Materials Wolfgang‐Pauli‐Str. 10, 8093 Zurich, Switzerland