1. Department of Physics, Institute of Science, Banaras Hindu University, Varanasi 221005, India
2. Atomic & Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India
3. UGC-DAE Consortium for Scientific Research, Indore 452017, India
4. Department of Physics, Indian Institute of Technology (BHU), Varanasi 221011, India
5. School of Materials Science and Technology, Indian Institute of Technology (BHU), Varanasi 221005, India