Berlin 2015 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 100: Metal Substrates: Adsorption and Reactivity

O 100.4: Vortrag

Freitag, 20. März 2015, 11:15–11:30, MA 043

IRRAS Investigation of Carbon Monoxide Adsorption on Pristine and Roughened Au(111) — •Jan Pischel and Annemarie Pucci — Kirchhoff-Institut für Physik, Im Neuenheimer Feld 227, D-69120 Heidelberg

The behavior of gold nanoparticles which are used, e.g., in surface enhanced spectroscopies [1] or heterogeneous catalysis [2], often critically depends on the properties of their surface.

While scanning tunneling microscopy as a well-suited method to explore the morphology of gold surfaces has already abundantly been applied [e.g. 3], we use infrared reflection absorption spectroscopy (IRRAS) in combination with CO adsorbed at cryogenic temperatures to probe the chemical properties of available sites at the surface. In this context, we present the first IRRAS investigation of CO adsorption on single crystalline Au(111) under ultra-high vacuum conditions. The interaction between CO and the flat surface is shown to differ significantly from that between CO and other types of gold surfaces known from literature. To make the connection, we introduced surface roughness in a well-defined manner by cold-depositing submonolayer amounts of gold onto the surface at 30K. Adsorption of CO on these rough surfaces is shown to result in the IR-response known from literature. A gradual transition between these two limiting cases can be realized by successively annealing the rough substrates.

[1] Neubrech, F. and A. Pucci, IEEE J. Select. Topics Quant. Electronics 19(3):4600809, 2013.  [2] Haruta, M., Gold Bulletin 37(1–2):27, 2004.  [3] Rai, A. et al., Surf. Sci. 625:97, 2014.