[1] NMAM Inst Technol, Dept Phys, Nitte 574110, Karnataka, India
[2] Bhuvanendra Coll, Dept Phys, Karkala, Karnataka, India
[3] Natl Inst Technol Karnataka, Dept Phys, Optoelect Lab, Mangalore 575025, India
[4] Mangalore Univ, Dept Chem, Mangalagangothri 574199, Karnataka, India
[5] PA Coll Engn, Dept Chem, Mangalore 574153, India