1. VTT Technical Research Centre of Finland, Tietotie 3, P.O. Box 1000, FI-02150 Espoo, Finland
2. VTT Technical Research Centre of Finland, Kaitoväylä 1, P.O.
Box 1100, FI-90571 Oulu, Finland
3. Eni S.p.A, Renewable Energy & Environmental R&D, Via Fauser 4, 28100 Novara, Italy
4. Department of Applied Physics, Aalto School of Science, P.O. Box 15100, FI-00076 Aalto, Finland
5. University of Oulu, Center of Microscopy and Nanotechnology, Erkki-Koisokanttilan katu 3, P.O. Box 7150, FI-90570 Oulu, Finland