1. Division of Science and Technology, Department of Physics , University of Education , Lahore , Pakistan
2. Department of Physics , COMSATS University Islamabad, Lahore Campus , Lahore , 54000 , Pakistan
3. Department of Physics , Government College University Lahore , Lahore, 54000 , Pakistan
4. Institut für Neurowissenschaften und Medizin, INM-5: Nuklearchemie, Forschungszentrum Jülich GmbH , D-52425 Jülich , Germany