Local control of single-molecule conductivity probed by scanning tunneling microscopy and
spectroscopy

Dr. Peter Wahl, Max-Planck-Institut für Festkörperforschung [Homepage]

Dr. Lucia Vitali, Max-Planck-Institut für Festkörperforschung [Homepage]

Prof. Dr. Klaus Kern, Max-Planck-Institut für Festkörperforschung [Homepage]

Electronic transport through a single molecule bonded to a metallic substrate will be studied by
local probe spectroscopy at low temperatures (0.5-6K). We complement morphology and
electronic structure of the molecules obtained by conventional scanning tunneling
microscopy/spectroscopy by transport properties extracted from point contact spectroscopy. This
combination offers a unique opportunity to deepen our understanding of the role of the electronic
and vibrational excitations in molecular electronic transport, and to address the determining role
of the molecule-metal contacts and the molecular conformation at a single molecule level and
with atomic-scale control over the contact area. Functional molecules with structural and/or
electronic bistability as building blocks of a future molecular electronics will be attached to
copper single crystal surfaces via a variety of bonding configurations (SH, SeH, NH2, CN,
COOH). The influence of the geometric and chemical structure on the molecule-metal contact
will be studied in detail. The effects of local defects, e.g. dopant atoms which are brought in
proximity to the molecule under investigation, are studied to explore the possibilities of local
conductance regulations.