1. Department of Physics, Middle East Technical University, 06800 Ankara, Turkey
2. Center for Solar Energy Research and Applications (GÜNAM), Middle East Technical University,06800 Ankara, Turkey
3. Institute of Nuclear Sciences, Hacettepe University, 06800 Ankara, Turkey
4. Department of Nanotechnology and Nanomedicine, Hacettepe University, Ankara, Turkey
5. Central Laboratory, Middle East Technical University, 06800 Ankara, Turkey
6. Faculty of Science, Department of Physics, Akdeniz University, 07058 Antalya, Turkey