1. Department of Applied Physics Eindhoven University of Technology P.O. Box 513 5600MB Eindhoven The Netherlands
2. Helmholtz Institute Erlangen‐Nürnberg for Renewable Energy (IEK‐11) Forschungszentrum Jülich Fürther Str. 248 90429 Nürnberg Germany
3. Department of Chemical and Biological Engineering and Department of Physics Friedrich‐Alexander‐Universität Erlangen‐Nürnberg Fürther Str. 248 90429 Nürnberg Germany