[1] Bangalore Univ, Dept Phys, Bangalore 560056, Karnataka, India
[2] Maharanis Sci Coll Women, Dept Phys, Bangalore 560001, Karnataka, India
[3] Indira Gandhi Ctr Atom Res, Radiol Safety Div, Kalpakkam 603102, Tamil Nadu, India
[4] MS Ramaiah Inst Technol, Dept Chem, Bangalore 560054, Karnataka, India