1. Institute of Physics, University of Szczecin, Wielkopolska 15, 70-451 Szczecin, Poland and Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Strasse 38, D-01187 Dresden, Germany
2. Department of Physical and Quantum Chemistry, Faculty of Chemistry, Wrocław University of Technology, Wybrzee Wyspiańskiego 27, 50-370 Wrocław, Poland