1. M. Smoluchowski Institute of Physics and Research Centre for Nanometer-Scale Science and Advanced Materials (NANOSAM), Jagiellonian University, Reymonta 4, 30-059 Kraków, Poland
2. Faculty of Physics and Applied Computer Science AGH-University of Science and Technology, al. Mickiewicza 30, 30-059 Kraków, Poland
3. Department of Physics and Electrical Engineering, Karlstad University, SE-651 88 Karlstad, Sweden
4. The Henryk Niewodniczański Institute of Nuclear Physics Polish Academy of Sciences, Radzikowskiego 152, 31-342 Kraków, Poland