1. Technical
Chemistry I, University of Duisburg-Essen and Center for NanoIntegration Duisburg-Essen CENIDE, Universtitaetsstrasse 5, 45141 Essen, Germany
2. Faculty
of Physics, University of Duisburg-Essen and Center for NanoIntegration Duisburg-Essen CENIDE, Lotharstr. 1-21, 47048 Duisburg, Germany