Stability of crystal facets in gold nanorods

Metal nanocrystals can be grown in a variety of
shapes through the modification of surface facet energies via
surfactants. However, the surface facets are only a few atoms
wide, making it extremely challenging to measure their
geometries and energies. Here, we locate and count atoms in
Au nanorods at successive time intervals using quantitative
scanning transmission electron microscopy. This enables us to
determine the atomic-level geometry and the relative stability
of the facets and to expound their relationship to the overall
three-dimensional nanocrystal shape and size. We reveal
coexisting high- and low-index facets with comparable stability
and dimensions and find the geometry of the nanorods is
remarkably stable, despite significant atom movements. This information provides unique insights into the mechanisms that
govern growth kinetics and nanocrystal morphology.