[1] Thiruvalluvar Univ, Dept Phys, Arignar Anna Govt Arts Coll, Vellore, Tamil Nadu, India
[2] Anna Univ, Univ Coll Engn Arni, Dept Phys, Chennai, TN, India
[3] VIT Univ, Dept Phys, Vellore, TN, India
[4] Thiruvalluvar Univ, Dept Phys, TVUCAS Campus, Thennangur, Tamil Nadu, India