Müller-Meskamp Lars, Karthäuser Silvia, Zandvliet Harold J W, Homberger Melanie, Simon Ulrich, Waser Rainer
Institute for Solid State Research (IFF) and JARA-FIT Research Center, Juelich GmbH, 52425 Jülich, Germany.
Small. 2009 Apr;5(4):496-502. doi: 10.1002/smll.200800802.
The electrical properties of alpha,omega-mercaptoalkyl ferrocenes with different alkyl chain lengths embedded in a self-assembled host matrix of alkanethiols on Au(111) are studied by scanning tunneling microscopy and spectroscopy. Based on current-distance spectroscopy, as well as on the evaluation of Fowler-Nordheim tunneling current oscillations, the apparent barrier height of ferrocene is determined independently by two methods. The electronic coupling of the ferrocene moiety to the Au(111) substrate is shown to depend on the length of the alkane-spacer chain. In a double tunnel junction model our experimental findings are explained, addressing the role of the different molecular moieties of the mercaptoalkyl ferrocenes.
