Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 10: New Methods and Developments II: Scanning Probe, Spectroscopic, and Diffraction Techniques

O 10.5: Vortrag

Montag, 1. April 2019, 16:00–16:15, H3

Single molecule nanotribology: understanding friction and adhesion at a single molecule level. — •J.G. Vilhena, Remy Pawlak, and Ernst Meyer — Department of Physics, University of Basel

Understanding the motion/dynamics of a single molecule over a surface is a problem of a paramount importance in the design of advanced molecular nanostructures/assemblies capable of meeting specific needs. Nevertheless, to date, understanding the interplay between molecule mechanics, surface displacements and dynamics at a atomic level is a highly challenging task since it requires the knowledge of not only the forces needed to manipulate them but also to relate them with particular molecular/atomic motion. Here we bridge this gap by combining MD simulations, scanning probe microscopy and force spectroscopy to investigate the manipulation of two different molecules (ssDNA and poly-pyrene) over a Au(111) surface in UHV at 5K. Our experiments/simulations revealed a contrasting on-surface dynamics of these molecules. The high ssDNA adhesion to Au(111) enabled us to chart the unexplored nano-Newton tensile force regime which allowed to quantify for the first time the stretching stiffness of a single DNA nucleotide. In the other extreme, the low adhesion and superlubric behavior of the poly-pyrene revealed a surprising complex on-surface dynamics of the molecule. Our simulations/experiments reveal a dynamic balancing between the intra-molecular mechanics and surface comensurability which result in a snake like motion of the molecule over the surface.