Dynamic Friction Unraveled by Observing an Unexpected Intermediate State in Controlled Molecular Manipulation

The pervasive phenomenon of friction has been studied at the nanoscale via a controlled manipulation of single atoms and molecules with a metallic tip, which enabled a precise determination of the static friction force necessary to initiate motion. However, little is known about the atomic dynamics during manipulation. Here, we reveal the complete manipulation process of a CO molecule on a Cu(110) surface at low temperatures using a combination of noncontact atomic force microscopy and density functional theory simulations. We found that an intermediate state, inaccessible for the far-tip position, is enabled in the reaction pathway for the close-tip position, which is crucial to understanding the manipulation process, including dynamic friction. Our results show how friction forces can be controlled and optimized, facilitating new fundamental insights for tribology.

Automated summary

This study reveals the complete manipulation process of a CO molecule on a Cu(110) surface using a combination of noncontact atomic force microscopy and density functional theory simulations. An intermediate state crucial for understanding dynamic friction is found in the reaction pathway during manipulation.