1. Institute of Physics, Technical University of Cracow, Podchorazych 1, Krakow, Poland
2. Electrical Engineering Department, Technological University of Czestochowa, Al. Armii Krajowej 17/19, Czestochowa, Poland
3. Department of Chemistry, Agricultural University of Krakow, ul. Balicka 122, 31-149 Krakow, Poland