1. Department of Physics and Astronomy; The University of Western Ontario; London N6A 3K7 Canada
2. Posgrado, Facultad de Arquitectura y Diseño; Universidad Autónoma del Estado de México; Toluca 50110 México
3. Department of Physics; Tuskegee University; Tuskegee AL 36088 USA
4. Physics Department; Beni-Suef University; Beni-Suef Egypt
5. Department of Physics; Bundelkhand University; Jhansi India