[1] Univ Calicut, Mercy Coll, Dept Phys, Palakkad 678006, India
[2] Univ Calicut, Govt Victoria Coll, Dept Phys, Palakkad 678001, India
[3] Cochin Univ Sci & Technol, Int Sch Photon, Kochi 682022, India
[4] Bharata Mata Coll, Dept Phys, Kochi 682021, India
[5] Cochin Univ Sci & Technol, Dept Polymer Sci & Rubber Technol, Kochi 682022, India
[6] Cochin Univ Sci & Technol, Inter Univ Ctr Nanomat & Devices IUCND, Kochi 682022, India