1. Department of Physics, Goverment Brennan College, Affiliated to Kannur University, Thalassery 670106, Kerala, India
2. Department of Physics, Payyanur College, Affiliated to Kannur University, Payyanur 670327, Kerala, India
3. Department of Physics, Pazhassi Raja N S S College, Affiliated to Kannur University, Mattanur 670702, Kerala, India