1. V.P. & R.P.T.P. Science College, Vallabh Vidyanagar 388120, Gujarat, India
2. Atomic and Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India
3. Homi Bhabha National Institute, Anushaktinagar, Mumbai 400085, India
4. P. D. Patel Institute of Applied Science, CHARUSAT, Changa 388421, Gujarat, India