1. Faculty of Physics and CENIDE
2. Universität Duisburg-Essen
3. 47057 Duisburg
4. Germany
5. Department of Physics
6. Ruhr-Universität Bochum
7. 44780 Bochum
8. University of Helsinki
9. Helsinki
10. Finland
11. Department of Physics and Astronomy
12. University of Pennsylvania
13. Philadelphia
14. USA
15. CIMAP
16. (CEA-CNRS-ENSICAEN-UNICAEN)
17. Caen
18. France
19. Department of Interface Science