1. Department of Physics, Cochin University of Science and Technology, Cochin 682 022, Kerala, India
2. On deputation from Department of Physics, Govt. Victoria College, Palakkad 678 001, Kerala, India
3. Department of Chemistry, St. Albert's College, Cochin 682 018, Kerala, India
4. Departments of Physics, Alphonsa College, Arunapuram P.O, Pala, Kottayam 686 574, Kerala, India
5. Department of Electronics, Cochin University of Science and Technology, Cochin 682 022, Kerala, India
6. Department of Polymer Science and Rubber Technology, Cochin University of Science and Technology, Cochin 682 022, Kerala, India
7. Physical and Materials Chemistry Division, National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India