1. Materials Science Department, University of Patras, 26504 Patras, Greece
2. Department of General Physics and Quantum Nanostructures, Russian-Armenian University, 123 Hovsep Emin Str., Yerevan 0051, Armenia
3. Institute of Chemical Physics after A.B. Nalbandyan of NAS RA, 5/2 Paruyr Sevak St., Yerevan 0014, Armenia
4. Key Laboratory for Special Functional Materials of Ministry of Education, Collaborative Innovation Center of Nano Functional Materials and Applications, and School of Materials Science and Engineering, Henan University, Kaifeng, Henan 475001, China
5. Institut für Physikalische Chemie, Universität Hamburg, Grindelallee 117, 20146 Hamburg, Germany