Unusual Adsorption Characteristics for Hydrogen on Gd Surfaces

In this part the electronic properties of chemisorbed hydrogen on Gd(OOOl) will be discussed. For the photoemission investigation, smooth Gd(OOOl) films were prepared and subsequently exposed to hydrogen. It was already shown in Sect. 3.1 (Chap. 3) that the Gd smface state exists both on smooth films and multilayer Gd islands. Therefore, multilayer island films were chosen for the STM investigations to provide topographical contrast in order to distinguish between sample states and tip induced artifacts as well as to determine the influence of different island heights. The detailed preparation procedure was already described in Sect. 3.1 (Chap. 3). 

Getzlaff, Surface Magnetism, Springer Tracts in Modem Physics, 240, 

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The chemistry of a surface determines the surface electronic properties. The following chapter was therefore focused on the influence of adsorbates. It was found that hydrogen exhibit unusual adsorption characteristics demonstrating a lagoon-like appearance. The incorporation of hydrogen in Gd thin films leads to a plastic deformation resulting in surface modihcations which were identified by STM. The combination of ultraviolet photoelectron spectroscopy (UPS) and STM allowed to determine the reaction scheme of coadsorption processes, exemplarily presented for hydrogen covered Gd surfaces exposed to CO. 

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