STM spectroscopy of magnetic molecules

We have investigated a series of magnetic supramolecular complexes involving coordinated metal ions. Using the current-imaging tunneling spectroscopy mode of a STM, we mapped isolated single molecules. By comparing with DFT calculations, we confirmed that the weakest bonds, i.e. the supramolecular coordination interactions, dominate the molecular orbitals near the Fermi-level of the molecule. Thus, STM spectroscopy can address directly the metal centers in a rather complex molecular entity. Our method allows a selective mapping of the functional units within the supramolecular architecture, even if these units are embedded into a complex set of organic ligands. We observed this behavior in all of our investigated molecules.