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Supporting results on the activation of 1D growth by increasing the deposition temperatureWe have studied the effect of deposition temperature (in the range of 300-1100 K) on the particle formation of Rh deposited onto a TiO 2 (110) surface. Naturally, upon increasing the deposition temperature, we have received more and more agglomerated particles (i.e. increased average particle size). More surprisingly, a dramatic change appeared in the particle shape: below 950 K, the particles were basically of round or slightly elongated shape; above this temperature, they exhibited a strongly elongated form. Image A (50 nm x 50 nm) shows the surface morphology at room temperature after the deposition of app. 1 ML of Rh at 850 K. All the particles thus formed have a nearly same width and length. Deposition of 5 ML of Rh at 1050 K results in the formation of highly elongated particles (image B). This property changes only moderately after 10 min annealing at 1050 K in vacuum (image C). The size of the images B and C is 400 nm x 400 nm.

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Gold based model systems exhibiting the structural versatility of nanoparticle ensembles and being accessible for surface spectroscopic investigations are expected to provide new information about the adsorption of carbon monoxide, a key process influencing the CO oxidation activity of this noble metal in nanoparticulate form. Accordingly, in the present work the interaction of CO is studied with an ion bombardment modified Au(111) surface by means of a combination of photoelectron spectroscopy (XPS and UPS), sum frequency generation vibrational spectroscopy (SFG), and scanning tunneling microscopy (STM). While no adsorption was found on intact Au(111), data collected on the ion bombarded surface at cryogenic temperatures indicated the presence of stable CO adsorbates below 190 K. A quantitative evaluation of the C 1s XPS spectra and the surface morphology explored by STM revealed that the step edge sites created by ion bombardment are responsible for CO adsorption. The identification of the CO binding sites was confirmed by density functional theory (DFT) calculations. Annealing experiments up to room temperature showed that at temperatures above 190 K unstable adsorbates are formed on the surface under dynamic exposure conditions that disappeared immediately when gaseous CO was removed from the system. Spectroscopic data as well as STM records revealed that prolonged CO exposure at higher pressures of up to 1 mbar around room temperature facilitates massive atomic movements on the roughened surface, leading to its strong reordering toward the structure of the intact Au(111) surface, accompanied by the loss of the CO binding capacity.