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In the era of nanoscinece and nanotechnology, numerous examples illustrating the saying “small is different” exist, i.e. nanoclusters. Scanning tunneling microscopy (STM) has proven to be a fascinating and powerful technique for revealing the atomic-scale realm of matter.
In this talk I will show how the unique aspect of our Aarhus STM to record time-resolved, high-resolution STM images, visualized in the form of STM movies can be used to obtain important new insight into the dynamics of surface processes and nanostructures [1-3]. First, I will discuss MoS2 nanoclusters, which are of interest in inorganic nanotubes, in nanoelectronics, and as the active nanoparticles in heterogeneous catalyst. By using STM to systematically map and classify the atomic-scale structure of triangular MoS2 nanoclusters as a function of size, we observed a distinct size dependence for the cluster morphology and electronic structure driven by the ten-dency to optimize the sulphur excess present at the cluster edges. [4].
Secondly, I will discuss the reactivity of Au nanoclusters on TiO2(110) surfaces in three different
oxidation states (i) reduced having bridging oxygen vacancies, (ii) hydrated having bridging hy-droxyl groups, and (iii) oxidized having oxygen adatoms. From an interplay of STM and DFT results we identify very surprisingly two different gold – TiO2(110) adhesion mechanisms for the reduced and oxidized supports, and that the adhesion of the Au clusters is strongest on the oxi-dized support [5].
References
1. F. Besenbacher, Reports on Progress in Physics 59, 1737 (1996)
2. R. Schaub et al., Science 299, 378 (2003); Science 303, 511 (2004)
3. S. Wendt et al., Physical Review Letters 96, 066107 (2006)
4. J.V. Lauritsen, et al Nature Nanotechnology 2, no. 1, 53 ( 2007)
5. D. Matthey, et al , Science (2007)
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