Abstrakt
Ferrocene-based molecules are extremely appealing as they offer a prospect of having built-in spin or charge functionality. However, there are only limited number of studies of structural and electronic properties on surfaces so far.
We investigated the self-assembly processes of 1,1'-ferrocene dicarboxylic acid molecules,(C12H10FeO4) on both metallic (Ag(111), Au(111), and Cu(110)) and insulating (Cu3N/Cu(110)) surfaces with high-resolution ncAFM/STM, XPS, and NXAFS. The experimental evidence is corroborated with total energy DFT calculations and ncAFM simulations.
The combined experimental and theoretical analysis allows detailed understanding of the unique arrangement and adsorption geometries of the molecules on different substrates, as well as the different chemical stability of the carboxylic (COOH) groups. The molecules on noble (Ag, Au) surfaces show only a weak interaction With the substrate forming a complex self-assembled pattern, driven by weak intermolecular interactions.
In contrast, the analysis reveals the carboxylic groups undergo dehydrogenation on the Cu(110) and Cu3N/Cu(110). As a-result, the oxygen atoms form strong chemical bands to the substrate Cu atoms and impose an orientation on the ferrocene cyclopentadienyl rings perpendicular to the substrate.