1. B.I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, Nezalezhnastsi Ave. 68, 220072 Minsk, Belarus
2. Institute of the Chemistry of New Materials, National Academy of Sciences of Belarus, F. Skaryna Str. 36, 220141 Minsk, Belarus
3. Institute of Electron Physics, Ukrainian National Academy of Sciences, 21 Universitetska Str., 88017 Uzhgorod, Ukraine