1. Institute of Applied Physics Problems, Kurchatov Street 7, 220045 Minsk, Belarus
2. Belarusian State University, Independence Ave. 4, 220030 Minsk, Belarus
3. Maria Curie-Skłodowska University, Pl. M. Curie-Skłodowskiej 1, 20-031 Lublin, Poland
4. Friedrich Schiller University Jena, Max-Wien-Platz 1, D-07743 Jena, Germany