1. Atomic friction of surfaces.  

    Mechanical forces on small scales provide valuable and detailed information on the properties of the probed surface, such as wear, friction and adhesion. Understanding the role of dissipation energy and surface potential in frictional mechanisms is essential for tribology, nanoscale fabrication, catalysis and so on. Through the interaction between the sharp Atomic Force Microscope (AFM) cantilever tip and the surface, various forces can be measured during the scanning experiment, and disclose information in the atomic-resolution. 

    We are interested in the application of nonequilibrium work relations to reconstruct the surface potential from such atomic friction measurements of mono-crystals and catalysts. In this context we are interested in probing the interaction potential between metal and oxide surface, and correlate it with the catalytic activity (conversion, selectivity etc.) of the studied substances.

    Going beyond catalysts, we study the mechanical properties of practical materials, such as semiconductors and alloys. We measure MoTe2 crystal in its metallic and semiconductor forms. Using lateral nanofriction and nanoindentation, we study the mechanical properties of aluminum alloy after chemical treatment of the surface when exposed to humidity, with the intention of correlating these properties with the adhesion of these surfaces with a polymeric adhesive matrix. We are also interested in fundamental investigation of measuring lateral friction on the nanoscale in the presence of liquid surrounding using the AFM.

  2. Single molecule force spectroscopy. 

    In recent years single molecule force spectroscopy techniques have evolved considerably, becoming an important measure in addition to traditional bulk methods. While ensemble bulk measurements study the averaged properties of a system, single molecule measurements illuminate the tails of these properties’ distributions. Atomic force microscopy (AFM), which has the ability to detect subtle details at sub-nanometer resolution, can hold a single protein for long periods of time, thus exploring a wide spectrum of forces ranging from a few to thousands of pico-Newtons. The single protein recorded force traces disclose its mechanistic features, such as reaction rates, diffusion coefficients, unfolding/refolding dynamics, free-energy landscapes available to perform work and conformational transition. We focus our interest on exploring proteins and polymers phase-transitions in the presence of co-solutes with the intention to provide new information about the physical-chemistry aspects of the specific ion phenomenon.   

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