Pyridine Adsorption on Single-Layer Iron Phthalocyanine on Au(111)

The adsorption of pyridine on monolayers of well-ordered, flat-lying iron phthalocyanine molecules on Au(111) is investigated by X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and density functional theory. It is found that pyridine both coordinates to the iron site of iron phthalocyanine and binds weakly to other sites. The iron coordination causes significant changes in the electronic structure of the iron phthalocyanine compound, with the implication of a change of the spin properties of the iron atoms due to the strong ligand field created by the pyridine axial ligand. Both low coverages and multilayer coverages of pyridine are considered. At low doses, the pyridine molecules are ordered, whereas in multilayers, no preferred orientation is observed. The orientation of the FePc molecules with respect to the Au(111) surface is not affected by the adsorption of pyridine