title: Imaging high-speed friction at the nanometer scale.
abstract: Friction is a complicated phenomenon involving nonlinear dynamics at different length and time scales. Understanding its microscopic origin requires methods for measuring force on nanometer-scale asperities sliding at velocities reaching centimetres per second. Despite enormous advances in experimental technique, this combination of small length scale and high velocity remain elusive. We present a technique for rapidly measuring the frictional forces on a single asperity over a velocity range from zero to several centimetres per second. At each image pixel we obtain the velocity dependence of both conservative and dissipative forces, revealing the transition from stick-slip to smooth sliding friction. We explain measurements on graphite using a modified Prandtl-Tomlinson model, including the damped elastic deformation of the asperity. With its improved force sensitivity and small sliding amplitude, our method enables rapid and detailed surface mapping of the velocity dependence of frictional forces with less than 10 nm spatial resolution.
authors.affiliation: Nanostructure Physics, Royal Institute of Technology (KTH), Albanova, SE-10791 Stockholm, Sweden.
authors.forename: Per-Anders
authors.initials: PA
authors.lastname: Thorén
authors.affiliation: Department of Physics, Stockholm University, 106 91 Stockholm, Sweden.|Department of Engineering Design and Materials, Norwegian University of Science and Technology, 7491 Trondheim, Norway.
authors.forename: Astrid S
authors.initials: AS
authors.lastname: de Wijn
authors.affiliation: Nanostructure Physics, Royal Institute of Technology (KTH), Albanova, SE-10791 Stockholm, Sweden.
authors.forename: Riccardo
authors.identifier: 0000-0001-8199-5510
authors.initials: R
authors.lastname: Borgani
authors.affiliation: Nanostructure Physics, Royal Institute of Technology (KTH), Albanova, SE-10791 Stockholm, Sweden.
authors.forename: Daniel
authors.initials: D
authors.lastname: Forchheimer
authors.affiliation: Nanostructure Physics, Royal Institute of Technology (KTH), Albanova, SE-10791 Stockholm, Sweden.
authors.forename: David B
authors.initials: DB
authors.lastname: Haviland