Elin Grånäs

Oxygen Intercalation under Graphene on Ir(111): Energetics, Kinetics, and the Role of Graphene Edges.

Using X-ray photoemission spectroscopy (XPS) and scanning tunneling microscopy (STM) we resolve the temperature-, time-, and flake size-dependent intercalation phases of oxygen underneath graphene on Ir(111) formed upon exposure to molecular oxygen. Through the applied pressure of molecular oxygen the atomic oxygen created on the bare Ir terraces is driven underneath graphene flakes. The importance of substrate steps and of the unbinding of graphene flake edges from the substrate for the intercalation is identified. With the use of CO titration to selectively remove oxygen from the bare Ir terraces the energetics of intercalation is uncovered. Cluster decoration techniques are used as an efficient tool to visualize intercalation processes in real space.

CO-Induced Smoluchowski Ripening of Pt Cluster Arrays on the Graphene/Ir(111) Moire

Regular Pt cluster arrays grown on the moiré template formed by graphene on Ir(111) were tested for their stability with respect to CO gas exposure. Cluster stability and adsorption-induced processes were analyzed as a function of cluster size, with in situ scanning tunneling microscopy and X-ray photoelectron spectroscopy. Small clusters containing fewer than 10 atoms were unstable upon CO adsorption. They sintered through Smoluchowski ripening-cluster diffusion and coalescence-rather than the frequently reported Ostwald ripening mediated by metal-adsorbate complexes. Larger clusters remained immobile upon CO adsorption but became more three-dimensional. Careful analysis of the experimental data complemented by ab initio density functional theory calculations provides insight into the origin of the CO-induced Pt cluster ripening and shape transformations.

Oxidation of Ultrathin FeO(111) Grown on Pt(111): Spectroscopic Evidence for Hydroxylation

Using high resolution and ambient pressure X-ray photoelectron spectroscopy we show that the catalytically active FeO

CO Intercalation of Graphene on Ir(111) in the Millibar Regime

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Carbonate formation on p(4 x 4)-O/Ag(111)

2 trilayer films grown on Pt(111) are very active for water dissociation, in contrast to inert FeO(111) bilayer films. The FeO

Hydrogen intercalation under graphene on Ir(111)

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