1. Department of Physics, Faculty of Science, Istanbul University, Vezneciler 34134 Istanbul, Turkey.
2. Selçuk University, Faculty of Science, Department of Physics, Campus 42075 Konya, Turkey.
3. Karamanoglu Mehmetbey University, Faculty of Science, Department of Physics, 70100 Karaman, Turkey.
4. Canakkale Onsekiz Mart University, Faculty of Arts and Sciences, Department of Physics, 17100 Canakkale, Turkey.
5. Hochschule für Technik und Wirtschaft Berlin, Wilhelminenhofstr. 75A, D-12459 Berlin, Germany.