1. Institute of Materials and Surface Engineering, Faculty of Materials Science and Applied Chemistry, Riga Technical University, Riga LV-1048, Latvia
2. Institute of Solid State Physics, University of Latvia, Kengaraga Street 8, Riga LV-1063, Latvia
3. School of Chemical and Biomedical Engineering, Faculty of Engineering and Information Technology, The University of Melbourne, Parkville 3010, Australia
4. School of Science, STEM College, RMIT University, Melbourne 3000, Australia