1. Physikalisches Institut and Center for Nanotechnology; Westfälische Wilhelms-Universität Münster; Heisenbergstrasse 11 D-48149 Münster Germany
2. Department of Nanotechnology and Nanomedicine; Hacettepe University; 06800 Ankara Turkey
3. Department of Chemistry; Biochemistry Division; Hacettepe University; 06800 Ankara Turkey