Submitted in partial fulfilment of the requirements for the Degree of Master of Science in Physics of Manonmaniam Sundaranar University, Tirunelveli during the year 2012. Under the guidance of Mrs. K. Lakshmi Nallathai, V.O. Chidambaram College, Tuticorin & Mr. C. Panneerselvam from EGRL, Tirunelveli.