You are cordially invited to the IPB COLLOQUIUM which will be held on Thursday, 6 March 2025 at 13:00 in the “Zvonko Marić” lecture hall of the Institute of Physics Belgrade. The talk entitled

The influence of surrounding media on nanoscale friction

will be given by Prof. Dr. Ronen Berkovich (Department of Chemical Engineering, Ben-Gurion University of the Negev, Israel). The abstract of the talk:

Single molecules at the interface of sliding contacts significantly impact tribological interactions at the nanoscale. Understanding these nanoscale friction mechanisms is essential for developing advanced engineered friction systems and surface characterization methods, particularly when operating in ambient atmospheric conditions or liquid environments. The presence of individual molecules rather than continuous films at single-asperity contacts profoundly influences the dynamics of the observed friction behaviors. Some studies suggest that the direct contact in liquid surroundings is dry, as liquid molecules are expelled from it, and the contact behaves as being under ultrahigh vacuum conditions. In this talk we will discuss the possibility that the surrounding media plays a role on the damping and dissipation mechanisms at the contact during friction. With the use of numerical simulation based on the Prandtl-Tomlinson model and experimental observations, we will show that the media can also greatly affect the elastic interaction and the damping state of the system. Our results raise the possibility that friction is affected not only by the properties of the solid contacting surfaces, but to some extent by the liquid molecules that are trapped in the sliding contact ("molecular lubrication” or “sub-boundary lubrication”). These findings have significant implications for understanding energy dissipation mechanisms at the nanoscale and may inform the design of nanoscale devices and lubricants.