Impact Of The Substrate Work Function On Self-Assembling And Electronic Structure Of Adsorbed Ruthenium Phthalocyanine

We report on a systematic study of bis-ruthenium phthalocyanine, (RuPc)(2), layers deposited on Au(111), Ag(111), and graphite. By scanning tunneling microscopy and density functional theory calculations, a detailed picture of the molecular orbitals rearrangement due to the contact with the substrate is drawn, which reveals a significant substrate impact on the molecule charge and spin patterns. On the metal substrates a reduction of the Ru-Ru dimer magnetic moment is observed due to the filling of a spin-down singly unoccupied molecular orbital. However, the higher work function of Au(111) induces a charge backdonation, which results in an unexpected spin polarization of the molecule ligand. On the other hand, the contact with graphite leaves the electronic and magnetic properties of (RuPc)(2) largely unaffected. The self-assembling process of the molecules on the different substrates has also been thoroughly investigated and interpreted in the light of molecular orbital rearrangements. On the low interacting graphite substrate, the process is mainly driven by molecule-molecule interactions leading to a square structure. Conversely, on Ag(111) and Au(111), the stronger molecule-substrate interaction produces a more complex scenario characterized by a manifold of structures.