1. International and Inter University Centre for Nanoscience and Nanotechnology, Mahatma Gandhi University; Kottayam 686 560 Kerala India
2. Pushpagiri Research Centre, Pushpagiri Institute of Medical Sciences & Research Centre; Tiruvalla 689 101 Kerala India
3. School of Pure and Applied Physics, Mahatma Gandhi University; Kottayam 686 560 Kerala India
4. School of Chemical Sciences, Mahatma Gandhi University; Kottayam 686 560 Kerala India