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Institute Methods and Instrumentation for Synchrotron Radiation Research

Surface dynamics and chemistry

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In a model adsorbate, the excitation in the molecule is first
converted into vibrational excitations, before a possible
transient state is populated. This state will be highly reactive and
important for catalysis. Eventually, the molecule will desorb from
the surface.

Chemical reactions on surfaces are the key to heterogeneous catalysis. More than 75% of all industrial chemicals are produced in catalytic reactions, where most often a well-designed solid surface offers an energetic landscape to selectively break bonds on the chemical ingredients and form the bonds of the chemical products. In very few selected systems a fundamental understanding only of the bonding configuration is available. We want to further this insight by studying the fundamentals of the surface chemical bond in selected model systems and how it reacts to different stimuli, like temperature, laser excitations, irradiation etc.

Furthermore, the basic coupling between the adsorbed atoms and molecules on the surface and the excitations in the underlying substrate are studied on a fundamental level. With time-resolved methods, we study the ultrafast evolution of the surface chemical bond on electronic time scales and we selectively prepare transient states (like precursors) that have not been available for spectroscopic analysis before, because of the short life time and low density of these states for static methods.

With the fundamental understanding of the energetic bonding structure of molecules on surfaces, their coupling and interaction and their evolution on electronic time scales, we think to gain a basic insight into the structures and energetics that can improve the specific design of catalyst surfaces, for example for very evolved functional cells like fuel cells and in connection with solar fuels.