1. Infrared Laser Spectroscopy Section, Physics Group, Bhabha Atomic Research Centre, Mumbai 400 085, India
2. Homi Bhabha National Institute, Anushaktinagar, Mumbai 400 094, India
3. Physics Department, Birla Institute of Technology and Science, Pilani 333031, Rajasthan, India
4. Harish-Chandra Research Institute, a CI of Homi Bhabha National Institute, Prayagraj, Allahabad, Uttar Pradesh 211019, India