1. National Centre for Physics, Quaid-i-Azam University Campus, Islamabad 45320, Pakistan
2. Atomic and Molecular Physics Laboratory, Department of Physics, Quaid-i-Azam University, Islamabad 45320, Pakistan
3. Department of Aerospace and Mechanical Engineering, University of Arizona, Tucson, AZ 85721, USA
4. Department of Mining and Geological Engineering, The University of Arizona, Tucson, AZ 85719, USA
5. School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology (NUST), Islamabad 44000, Pakistan