1. Department
of Chemistry, Jadavpur University, Kolkata 700 032, India
2. Department
of Physics, M. G. Mahavidyalaya, Bhupatinagar, Purba Medinipur, West Bengal 721 425, India
3. Central Chemical Laboratory, Geological Survey of India, 15 A & B Kyd Street, Kolkata 700 016, West Bengal, India
4. Departament
de Química, Universitat de les Illes Balears, Crta. de Valldemossa
km 7.5, 07122 Palma (Baleares), Spain