1. Department of Physics , The Hindu College, Krishna University , Machilipatnam 521001 , India
2. LCRC-R&D, Department of ECE , Koneru Lakshmaiah Education Foundation , Guntur 522502 , India
3. Department of Physics , Yogi Vemana University , Kadapa , India
4. Department of Chemistry , Krishna University , Machilipatnam 521001 , India
5. Department of Nanotechnology , Acharya Nagarjuna University , Guntur , India
6. Department of Physics , Andhra Loyola College , Vijayawada 520008 , India