Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 42: Poster Session II (Nanostructures at surfaces: arrays; Nanostructures at surfaces: Dots, particles, clusters; Nanostructures at surfaces: Other; Nanostructures at surfaces: Wires, tubes; Metal substrates: Adsorption of O and/or H; Metal substrates: Clean surfaces; Metal substrates: Adsorption of organic/bio moledules; Metal substrates: Solid-liquid interfaces; Metal substrates: Adsorption of inorganic molecules; Metal substrates: Epitaxy and growth; Heterogeneous catalysis; Surface chemical reactions; Ab-initio approaches to excitations in condensed matter; Organic, polymeric, biomolecular films– also with adsorbates; Particles and clusters)
O 42.109: Poster
Mittwoch, 25. März 2009, 17:45–20:30, P2
On the fate of hydrogen by formation of thiol-based self-assembled monolayers: A critical in situ photoelectron spectroscopy result — •Laxman Kankate, Andrey Turchanin, and Armin Gölzhäuser — Fakultät für Physik, Universität Bielefeld, 33615 Bielefeld
Self-assembled monolayers (SAMs) of thiols on gold are vastly utilized for the functionalization of surfaces and interfaces in interdisciplinary research for many years. However, a seminal question on the fate of the hydrogen of the S-H groups upon SAM formation has not been answered unambiguously1. It is generally believed that the S-H bond scission takes place and the released hydrogen either sticks to the surface or desorbs in the molecular form. Some studies, however, suggest that the S-H bond scission does not occur at all. Here, we present the experimental results which clearly show that the atomic hydrogen forms upon thiol SAM formation and interacts with the monolayer terminus. Vapour phase deposition was utilized to grow 4′-nitro-1,1′-biphenyl-4-thiol, 4-nitrophenylthiol and bis-(4,4′-nitrobiphenyl)-disulphide SAMs on Au surfaces. Using in situ x-ray photoelectron spectroscopy (XPS) we found that the terminal nitro group of the thiol SAMs are partially reduced upon the self-assembly into the amino group. On the contrary, the disulphide SAMs form without any reduction.
[1] J.C. Love, L.A. Estroff, J.K. Kriebel, R.G. Nuzzo, G.M. Whitesides, Chem. Rev. 105 (2005) 1103