1. Institute of Physics, Cracow Pedagogical University, Ul. Podchorążych 2, 30-84 Kraków, Poland
2. Institute of Physics, University of Silesia, Ul. 75 Pułku Piechoty 1, 41-500 Chorzów, Poland
3. Institute of Applied Physics, Military University of Technology, Ul. Gen. S. Kaliskiego 2, 00-908 Warsaw, Poland