Affiliation: | (1) Physics Department, Kumaun University, 263 001 Nainital, India;(2) Physics Department, Aligarh Muslin University, 202 001 Aligarh, India;(3) Physics Department, Osmania University, 500 007 Hyderabad, India;(4) Present address: Physics Department, Oliver Lodge Laboratory, University of Liverpool, (U.K.) |