1. Department of Physics, Ernst-Moritz-Arndt University of Greifswald, Felix-Hausdorff-Strasse 6, D-17489 Greifswald, Germany
2. Institute of Pharmacy, Ernst-Moritz-Arndt University of Greifswald, Friedrich-Ludwig-Jahn-Strasse 17, D-17489 Greifswald, Germany