Bonding and reaction of self-assembled monolayers on ferromagnetic metal surfaces

F. BLOBNER; P. N. ABUFAGER; F. ALLEGRETTI; H.F.BUSNENGO; K. REUTER; P. FEULNER

Conferencia; 29 ECOSS European Conference on Surface Science; 2012

While thiolate bonded self-assembled monolayers (SAMs) on gold and other inert metal surfaceshave been widely investigated in the past decades, studies of such SAMs on the more reactive 3dferromagnetic metals are comparatively rare, despite the envisaged role of these interfaces inmolecular spintronics [1]. Here, we report on the adsorption geometry and stability of aromaticSAMs with backbone composed of a single phenyl ring and different ligands as endgroups, depositedin ultra high vacuum (UHV) on single crystal surfaces and/or thin films of Ni(111) and Co(0001). By  means of high-resolution X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption finestructure (NEXAFS) and thermal desorption spectroscopy (TDS) in conjunction with density functionaltheory (DFT) calculations we get insight into the molecule integrity and bonding configuration andcast light onto decomposition reactions that may occur at different temperatures and coverages. Inparticular, we investigate systematically preparation induced effects, aiming to reconcile the puzzleof conflicting evidence on SAMs prepared in solution [2] and UHV [3]. Two molecules are investigated, where the ligands are one F atom and a CN group respectively, and the comparisonwith more ordinary benzenethiolate SAMs enables to highlight the influence of endgroups andcharge redistribution in the aromatic ring on the stability of the thiolate-metal bond, the molecularconformation and packing.[1] A.R. Rocha et al., Nat. Materials 4 (2005) 3.[2] P.G. Hoertz et al., J. Am. Chem. Soc. 130 (2008) 9763, and references therein.[3] T.S. Rufael et al., J. Phys. Chem. 98 (1994) 13022.