1. Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada
2. Molecular Electronics, Department of Electrical and Computer Engineering, Technical University of Munich, 80333 Munich, Germany
3. Center for NanoScience (CeNS), Ludwig-Maximilians-University, 80539 Munich, Germany
4. Fraunhofer Research Institution for Microsystems and Solid State Technologies (EMFT), 80686 Munich, Germany