1. Laboratory of Interfaces and Nanosize Systems, Institute of Chemistry, Eötvös Loránd University, Pázmány Péter stny. 1/a, H-1117 Budapest, Hungary, and HAS Research Group of Technical Analytical Chemistry, Szt. Gellért tér 4, H-1111 Budapest, Hungary
2. Department of Physics, University of Trento, via Sommarive 14, I-38050 Povo, Trento, Italy, and Frankfurt Institute for Advanced Studies, J. W. Goethe University, Ruth-Moufang Str. 1, D-60438 Frankfurt, Germany
3. Department of Physics, University of Trento, via Sommarive 14, I-38050 Povo, Trento, Italy