1. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, ulitsa Vavilova 28, Moscow 117813, Russia
2. Department of Physics, Moscow State University, Vorob'evy gory, Moscow 119899, Russia
3. Institute of Macromolecular Chemistry "P Poni ", 41A Grigore Ghica Voda, Jassy, 6600 Romania