[1] Thiruvalluvar Govt Arts Coll, Dept Phys, Rasipuram 637401, Tamil Nadu, India
[2] Thiru A Govindasamy Govt Arts Coll, Dept Phys, Tindivanam 604307, Tamil Nadu, India
[3] Govt Arts Coll Women, Dept Phys, Salem 636008, Tamil Nadu, India
[4] Govt Arts Coll Autonomous, Dept Phys, Salem 636007, Tamil Nadu, India
[5] Univ South Africa UNISA, Coll Grad Studies, UNESCO UNISA Africo Chair Nanosci Nanotechnol Labs, POB 392, Pretoria, Gauteng Provinc, South Africa
[6] Natl Res Fdn NRF, Nanosci African Network NANOAFNET, iThemba LABS, Mat Res Grp MRG, 1 Old Faure Rd,7129 Somerset West,POB 722, ZA-7129 Pretoria, Western Cape Pr, South Africa