| AVS 63rd International Symposium & Exhibition | |
| Surface Science | Tuesday Sessions |
| Session SS-TuP |
| Session: | Surface Science Poster Session |
| Presenter: | Sabine Auras, Leiden University, Netherlands |
| Authors: | S.V. Auras, Leiden University, Netherlands J. Janlamool, Chulalongkorn University, Bangkok |
| Correspondent: | Click to Email |
Many heterogeneously catalyzed reactions have been shown to be strongly structure dependent.[1] Catalytically active materials can feature a wide spectrum of defect densities on the same sample and may include various step types.[2] Thus, curved crystals with continuously changing average step densities provide a good alternative to flat single crystals for the investigation of surface structure dependencies.[3] In this study we use two curved Ag single crystals to exemplify the strength of this approach to studying structure dependencies. The crystals have two different apex orientations. One Ag crystal with a [111] apex contains two different step sites on either side of the center, generally referred to as the (100) and (111) or A and B step types. The step density gradually increases until at the edges of the crystal we reach 5-atom wide (111) terraces. The crystal with the [100] apex has only one step type, that resembles the B step type from the first crystal, but has adjacent (100) terraces. We study the surface structure of the clean crystals with LEED and STM and show that the surface behaves as may be expected with single-atom high steps.
Subsequently, water adsorption to the steps and their effect on the water-metal interface are investigated using spatially resolved Temperature Programmed Desorption. As Ag binds water only weakly, effects resulting from the available steps are expected to be rather small . We show how the different step types affect the desorption of water and how it would be nearly impossible to measure the effects using multiple flat Ag samples.
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