The photo-induced reaction dynamics of adsorbate molecules on well-defined ultra-thin oxide films and on supported metal particles is investigated using femtosecond laser pump-probe mass spectrometry with resonance enhanced multi-photon ionization detection. It is demonstrated that this technique is able to reveal the real-time dynamics of the transition state and the product formation in a surface-aligned photoreaction as a function of oxide film thickness and cluster size.<br/> <br/>In addition, a new experimental setup is presented in which metal supported graphene layers serve as template to grow regular metal cluster nano-structures for molecular adsorption and photodissociation. The bound unoccupied electronic state structure of an Ir(111)/graphene surface covered by differently sized and spaced Ir clusters was characterized by means of femtosecond two-photon photoemission spectroscopy. The cluster lattice was found to affect the image potential states of the substrate to an extent, which is surprisingly large compared to the graphene area covered by Ir clusters. This effect can be related to the influence of the cluster lattice on the screening of the image state electron trapped in front of the surface. Furthermore, lateral confinement effects could be observed due to the decreasing extension of bare graphene areas. Finally, the adsorption and photoreaction of molecules on these cluster lattices is investigated by scanning tunneling microscopy.<br/>

Ultrafast photochemistry on oxide surfaces and supported metal clusters

256th National Meeting (2018)

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