1. NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza S. Silvestro 12, I-56127 Pisa, Italy
2. Faculty of Chemistry, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland
3. Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Daxue Road 1001, 30010 Hsinchu, Taiwan
4. Institute of Physical Chemistry, Karlsruhe Institute of Technology, Fritz-Haber Weg 2 (Geb. 30.44), D-76131 Karlsruhe, Germany
5. MOLTECH-Anjou, UMR 6200, CNRS, Université Angers, 2 bd Lavoisier, 49045 Angers Cedex, France
6. Dipartimento di Fisica, Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy