1. Department
of Physics, Banaras Hindu University, Varanasi-221005, Uttar Pradesh, India
2. Department
of Physics, Indian Institute of Technology (BHU), Varanasi-221005, Uttar Pradesh, India
3. Instituto
de Ciencias Físicas, Universidad Nacional Autonoma de Mexico, Cuernavaca, Morelos, 62210, México
4. Department
of Zoology, Banaras Hindu University, Varanasi-221005, Uttar Pradesh, India