1. PG & Research Department of Physics, Government Arts College (Affiliated to Bharathidasan University), Ariyalur 621713, India
2. School for Advanced Research in Petrochemicals: Laboratory for Advanced Research in Polymeric Materials, Central Institute of Petrochemicals Engineering and Technology, Bhubaneswar 751024, India
3. Department of Physics, University of Konstanz, Universitätsstr. 10, P.O.B-680, Konstanz 78457, Germany