Entire scientific disciplines such as mechanics and chemistry are governed by the interactions between atoms and molecules. On surfaces, forces extending into the vacuum direct the behavior of many scientifically and technologically important phenomena such as corrosion, adhesion, thin film growth, nanotribology, and surface catalysis. To advance our knowledge of the fundamentals governing these subjects, it would be useful to simultaneously map electron densities and quantify force interactions between the surface of interest and a probe with atomic resolution. For example, in the case of a catalytically active surface, this would allow to study the role and effectiveness of surface defects such as vacancies, kinks, impurities, and domain boundaries as active sites. Nanotribological research, i.e., the study of the atomic origins of friction, would be aided by the availability of a method able to lateral forces with atomic specificity.
We will start this talk by shortly reviewing the operational principles of scanning tunneling microscopy (STM) and atomic force microscopy (AFM), two probe-based microscopy methods that are able to achieve atomic-resolution imaging of surfaces. Subsequently, we describe recent efforts to characterize a surface’s structure by enabling species-specific atomic resolution imaging and quantify chemical interaction strengths in three dimensions with picometer and piconewton resolution using noncontact atomic force microscopy and outline how this information can be combined with local electronic information. Applications to explore topics such as surface chemistry or the atomic origins of friction will be presented for various model systems including oxides, metals, ionic crystals, and layered materials, with the ultimate goal to obtain a complete toolbox for the single-atom and single-molecule characterization that far exceeds simple atomic imaging.
Udo D. Schwarz Professor of Mechanical Engineering and Materials Science and Chemical and Environmental Engineering, Yale University.
Udo D. Schwarz graduated in 1989 from the University of Basel, Switzerland, receiving his Ph.D. in physics from the same institution in 1993. Subsequently, he continued his work as a staff scientist and lecturer at the Institute of Applied Physics of the University of Hamburg, Germany. In 2001, Prof. Schwarz moved to the Materials Science Department of the Lawrence Berkeley National Laboratory in Berkeley, California. Since 2002, he works at Yale’s Mechanical Engineering Department, where he got promoted to full professor in 2009 and serves as department chair since 2012. His research interests concern the local measurement of atomic-scale interactions and properties, including electric, magnetic, chemical, and nanotribological interactions, using scanning probe microscopy techniques to study problems in surface physics, catalysis, friction, and adhesion.