1. Department of Applied ChemistryCochin University of Science and Technology Kochi 682 022 Kerala India
2. Laser and Nonlinear Optics Laboratory, Department of PhysicsNational Institute of Technology Calicut 673 601 India
3. Department of ChemistrySchool of Physical Sciences, Central University of Kerala Tejaswini Hills, Periye Kasaragod 671 320 India