1. Department of Physics, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641 020, India
2. Nano-crystal Design & Application Lab (n-DAL), Department of Physics, PSG Institute of Technology and Applied Research, Coimbatore-641 020, Tamil Nadu, India
3. Centre for Clean Energy and Nano Convergence, Hindustan Institute of Technology and Science, Chennai-603 103, Tamil Nadu, India