1. Department of Physics, Jordan University of Science & Technology, P.O. Box 3030, Irbid 22110, Jordan
2. Leibniz Institut für Analytische Wissenschaften-ISAS-e.V., Bunsen-Kirchhoff-Straße 11, 44139 Dortmund, Germany
3. Department of Physics, Khalifa University of Science and Technology, Abu Dhabi P.O. Box 127788, United Arab Emirates
4. Nanotechnology Center for Scientific Research, The University of Jordan, Amman 11942, Jordan
5. Department of Physics, University of Nebraska at Omaha, Omaha, NE 68182, USA