1. St. Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg 199034 Russia
2. Department of Physics, LUT University, Box 20, Lappeenranta 53851, Finland
3. St. Petersburg National Research University of Information Technologies, Mechanics and Optics (ITMO University), Kronverkskiy pr. 49, St. Petersburg 197101 Russia
4. Tver State University, Zhelyabova st., 33, Tver 170100 Russia
5. Institute of Macromolecular Compounds, Russian Academy of Sciences, Bolshoy Prospect 31, V.O., St. Petersburg 199004 Russia