Nanoscale Friction Varied by Isotopic Shifting of Surface Vibrational Frequencies
Rachel J. Cannara,1*
Matthew J. Brukman,2
Katherine Cimatu,3
Anirudha V. Sumant,2
Steven Baldelli,3
Robert W. Carpick2
Friction converts kinetic energy at sliding interfaces into lattice vibrations, but the detailed mechanisms of this process remain unresolved. Atomic force microscopy measurements reveal that changing the mass of the terminating atoms on a surface, and thus their vibrational frequencies, affects nanoscale friction substantially. We compared hydrogen- and deuterium-terminated single-crystal diamond and silicon surfaces, and in all cases the hydrogenated surface exhibited higher friction. This result implies that the lower natural frequency of chemisorbed deuterium reduces the rate at which the tip's kinetic energy is dissipated. This discovery is consistent with a model describing energy transfer to adsorbates from a moving surface.
1 Department of Physics, University of Wisconsin–Madison, Madison, WI 53706, USA.
2 Department of Engineering Physics, University of Wisconsin–Madison, Madison, WI 53706, USA.
3 Department of Chemistry, University of Houston, Houston, TX 77004, USA.
* Present address: IBM Research GmbH, Zurich Research Laboratory, 8803 Rüschlikon, Switzerland.
Present address: Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA.
Present address: Center for Nanoscale Materials, Argonne National Laboratory, Argonne, IL 60439, USA.
Present address: Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, PA 19104, USA.
