1. Faculty of ChemistryUniversity of OpoleOleska 48, Opole45‐052 Poland
2. Department of Materials PhysicsOpole University of TechnologyKatowicka 48, Opole45‐061 Poland
3. Institute of Physics, University of OpoleOleska 48, Opole45‐052 Poland
4. University of Bielsko‐BiałaWillowa 2, Bielsko‐Biała43‐300 Poland
5. Centre for Advanced Technologies, Adam Mickiewicz University in PoznańUmultowska 89C, Poznań61‐614 Poland