1. Institute of Experimental Botany, Czech Academy of Sciences, Rozvojová 313, 165 00 Prague 6, Lysolaje, Czech Republic
2. Institute of Plasma Physics of the Czech Academy of Sciences, U Slovanky 2525/1a, 182 00 Praha 8, Czech Republic
3. Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00 Prague, Czech Republic
4. Department of Macromolecular Physics, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 180 00 Prague, Czech Republic