1. Center for advanced materials, Qatar University, Doha 2713, Qatar
2. Gas Processing Center (GPC), College of Engineering, Qatar University, Doha 2713, Qatar
3. Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Private Bag 3, PO Wits, Johannesburg 2050, South Africa
4. Petroleum and Chemical Engineering Department, Sultan Qaboos University, Muscat, Oman
5. Institute of Atomic Physics and Spectroscopy, University of Latvia, 19 Raina Blvd., LV-1586 Riga, Latvia