1. Technische Universität Darmstadt, Institute of Materials Science, Surface Science Division, Petersenstrasse 32, 64287 Darmstadt, Germany
2. Ecole Polytechnique Fédérale de Lausanne (EPFL), Institut des Sciences et Ingénierie Chimiques,
Laboratory of Photonics and Interfaces, Station 6, CH-1015 Lausanne, Switzerland
3. i3N/CENIMAT, Universidade NOVA de Lisboa and CEMOP/UNINOVA, Department
of Materials Science, Faculty of Science and Technology, Campus de Caparica, 2829-516 Caparica, Portugal