Study of Ferrocene Dicarboxylic Acid on Substrates of Varying Chemical Activity
journal contributionposted on 22.08.2016, 00:00 by J. Berger, K. Kośmider, O. Stetsovych, M. Vondráček, P. Hapala, E. J. Spadafora, M. Švec, P. Jelínek
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 NEXAFS. 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 bonds to the substrate Cu atoms and impose an orientation on the ferrocene cyclopentadienyl rings perpendicular to the substrate.
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NEXAFSchemical stabilityself-assembled patternXPSadsorption geometriessurfaces showferrocene cyclopentadienyl ringsVarying Chemical Activity Ferrocene-based moleculescharge functionalityCOOHinteractioncarboxylic groupsC 12 H 10 FeO 4oxygen atoms formFerrocene Dicarboxylicself-assembly processesAgenergy DFT calculationsncAFM simulationsanalysissubstrate Cu atomschemical bonds