Working group 4

The aim is a predictive understanding and control of the fundamental processes underlying nanofriction and adhesion by exploiting nano-object manipulations. This strategy can serve as a complementary method to study interfacial friction as a function of parameters difficult to access and modify in a standard FFM set-up. For example nanoparticles allow a broader choice of structurally well-defined material pairings at the interface and /or permit to vary the contact size over a wide range.

Main objectives

  • Control the dynamics of nanoparticles using AFM, understanding the influence of friction forces on translational and rotational motion on the nanoscale.
  • Clarify the role of size, shape, geometry, and electronic structure in the manipulation of nanoparticles.
  • Explore the detailed mechanisms at the onset of sliding as a function of cluster size, to obtain new insight in the yet unsolved issue of how friction depends on the contact area and age.
  • Investigate the mechanisms of controlled AFM manipulation of atoms/molecules at insulating surfaces.
  • Understand single-atom manipulation mechanisms depending on the adatom-surface binding character.

Methods A

Experimental: *Protocol implementation for AFM controlled nanomanipulation in controlled atmosphere, liquids, ultra-high vacuum. *Optimizing in-situ friction measurements during crystalline nanoparticle manipulation on amorphous or well-ordered substrates. *Exploiting multichannel multi-frequency AFM acquisition protocols for the simultaneous observation of manipulation process.

Methods B

Theoretical: *Analysis of the contact-area, interfacial shear-stress, and shear-strength dependences on the shape of gold nanoparticles. *MD simulations of the detailed depinning mechanisms and the most effective energy dissipation processes in the dynamics of deposited nanoclusters. *DFT simulations and STM/AFM measurements of single-atom manipulation in ultrahigh vacuum. *Developing simplified models based on classical mechanics and reaction-rate theory to interpret nanomanipulation experiments.