1. Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, Prague 2, CZ-12116, Czech Republic
2. Institute of Physics, Charles University, Ke Karlovu 5, Prague 2, CZ-12116, Czech Republic
3. Laboratory of Physics and Helsinki Institute of Physics, Helsinki University of Technology, P.O. Box 1100, FI-02015 HUT, Finland
4. Institute of Physics, Tampere University of Technology, P.O. Box 692, FI-33101 Tampere, Finland, Laboratory of Physics and Helsinki Institute of Physics, Helsinki University of Technology, P.O. Box 1100, FI-02015 HUT, Finland, and MEMPHYSCenter for Biomembrane Physics, University of Southern Denmark, Odense, Finland