1. Department of Physics, International Islamic University, Islamabad, Pakistan
2. Department of Physics, Durham University, South Road, DH1 3LE Durham, United Kingdom
3. Laboratory of Nanoscience and Technology, Department of Physics, Quaid i Azam University, Islamabad, Pakistan
4. Institute of Biomedical and Genetic Engineering (IBGE), Islamabad, Pakistan
5. Experimental Physics Labs, Professor Abdus Salam Centre of Physics, Islamabad, Pakistan