1. University of Jyvaskyla, Department of Chemistry, Nanoscience Center, P.O. Box 35, 40014 University of Jyvaskyla (Finland)
2. University of Tartu, Institute of Physics, Ravila 14c, 50411 Tartu (Estonia)
3. Tofwerk AG, Uttigenstrasse 22, 3600 Thun (Switzerland)
4. University of Jyvaskyla, Nanoscience Center, Department of Biological and Environmental Science, P.O. Box 35, 40014 University of Jyvaskyla (Finland)