1. Institute of Technology for Nanostructures (NST), University Duisburg-Essen, Duisburg D-47057, Germany
2. Center for Nanointegration Duisburg-Essen (CENIDE), University Duisburg-Essen, Duisburg D-47057, Germany
3. Institute for Combustion and Gasdynamics–Fluid Dynamics (IVG), University Duisburg-Essen, Duisburg D-47057, Germany