Oberflächenphysik

Diebold`s research activities lie at the interface between physics and chemistry, and she has earned worldwide renown as a leading expert in metal oxide surfaces. Her specialty is the application of scanning tunneling microscopy (STM) and surface spectroscopy techniques in order to observe, describe and understand the surface structures and molecular processes of metal oxides down to the atomic level. Diebold`s success in science and research essentially rests on three pillars: the systems she chooses, her ability to conduct precise and ground- breaking experiments, and her talent for leading research teams to outstanding achievements. Her research work centres on oxidised materials. On the one hand, this focus represents a logical decision: As all metals and semiconductors eventually oxidise when exposed to the environment, it is worth studying their oxide compounds in order to learn more about their surfaces. At the same time, these materials have a fascinating range of physical and chemical properties. Metal oxides include the best insulating materials and superconductors; some can be used as particularly active catalysts, while others are known to be especially corrosion-resistant. Coupled with the possibility of influencing their properties, this versatility makes metal oxides highly promising for a wide variety of technical applications. In practically all of the current and imaginable future applications of these materials such as catalysts, gas sensors, batteries, fuel cells and innovative electronic components their surfaces and interfaces play a key role. As a result, research on fundamental questions of surface properties and processes is not only of interest to the scientific disciplines per se, but it also has a major impact on issues related to environmental protection, energy resources and storage, as well as other broad areas of technical application. As a young faculty member at Tulane University, Ulrike Diebold already began to investigate fundamental questions of surface science in metal oxides in the 1990s. At the time, metal oxides were considered an interesting field, but they were considered too complex and too "messy" to enable meaningful surface research. Diebold was the first to demonstrate that it is possible to use STM to make atomic-scale material defects visible, and that it is possible to observe the chemical reactions triggered by those defects molecule for molecule. She joined forces with the world`s top theoretical groups in order to model the findings resulting from her experiments and thus to attain a better understanding of how chemical reactions occur on surfaces. Both her highly cited review articles as well as her original works have had a major impact on the entire field of surface science. In the future, Diebold and her team plan to concentrate on applying new methods to investigate solid-liquid interfaces. With the Wittgenstein Award, she will be able to intensify her efforts to explore uncharted territory in surface science using an electrochemical scanning tunneling microscope.

The Wittgenstein Prize and the associated project funds allowed expanding our research laboratories' experimental and methodological capabilities. Our research group now holds an internationally leading position in surface physics. In this field, the aim is to understand how atoms arrange themselves on surfaces, how individual molecules stick to them and change their bonds, and how suitable modifications can judiciously influence this. This fundamental research is also relevant for a variety of applications. For example, the materials mainly studied in our group, oxides, play a central role in energy conversion processes. A novel type of atomic force microscope was purchased and adapted to study oxides to study surfaces in even greater detail. We had to overcome some initial difficulties. For example, it was necessary to invent a new suspension system for the equipment, which weighs several tons. This isolation system has since been patented and allows precise experiments despite the vibrations present in a high-rise building. The microscope now provides images with unprecedented resolution. In collaboration with groups working theoretically, these experimental results have led to several scientific breakthroughs: the manipulation of single defects, the targeted placement of electrons on single oxygen atoms, or the determination of the acidity of single surface atoms. Furthermore, we have devised innovations to investigate the influence of liquid water on surfaces under ultrapure conditions. The "likely cleanest water drop in the world" produced in this process has attracted international attention. It is gratifying that these scientific results could be used as a basis for the successful acquisition of further research projects, including two ERC grants, a START award, a new SFB called TACO, and an Elise Richter grant. Even more gratifying is that these developments have helped some former staff members to start their independent academic careers.