1. Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznań, Poland
2. Laboratoire CRISMAT, UMR 6508 CNRS-ENSICAEN 6, Boulevard du Maréchal Juin, 14050 Caen Cedex, France
3. Institute of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland