1. Manonmaniam Sundaranar University, Tirunelveli, Tamil Nadu, India
2. Department of Physics and Research Centre, Nesamony Memorial Christian College, Marthandam, India
3. Department of Chemistry, NSS College Ottapalam, Palakkad, India
4. Department of Physics, Centre for Molecular and Biophysics Research, Mar Ivanios College, Thiruvananthapuram, India