1. Department of Chemistry, University of North Bengal, Darjeeling-734013, India
2. Department of Chemical Sciences, Indian Institute of Science Education and Research, Mohali, Sector 81, Knowledge City, S. A. S. Nagar, Manauli PO, Mohali, Punjab 140306, India
3. Composite Materials Research Laboratory, Department of Physics and UGC-HRDC, University of North Bengal, Darjeeling-734013, India