1. Department of Chemistry, Periyar University, Salem 636 011, Tamilnadu, India
2. Centre for Nanoscience and Nanotechnology, Periyar University, Salem 636 011, Tamilnadu, India
3. Department of Physics, School of Basic and Applied Sciences, Central University of Tamilnadu, Thiruvarur-610 101, Tamilnadu, India