Figure 1
M. Feldmann & J. Sondhauss/Univ. of Giessen; APS/Joan Tycko

Friction under the microscope. This scanning electron microscope image shows the atomic force microscopy tip as it prepares to push an antimony nanoparticle along the graphite surface (top). The larger a nanoparticle, the larger the mismatch of its atoms with the potential energy valleys of the bottom surface. This mismatch results in lower friction than would otherwise be expected.