1. Department of Physics, Durham University, South Road, Durham DH1 3LE, United Kingdom
2. Faculty of Chemistry, Silesian University of Technology, Ks. M. Strzody 9, 44-100 Gliwice, Poland
3. Centre of Polymer and Carbon Materials, Polish Academy of Sciences, M. Sklodowskiej-Curie 34, 41-819 Zabrze, Poland