Three-dimensional atomic-scale structure of size-selected nanoclusters on surfaces

Abstract

An unambiguous determination of the three-dimensional structure of nanoparticles is challenging. Electron tomography requires a series of images taken for many different specimen orientations. This approach is ideal for stable and stationary structures. But ultrasmall nanoparticles are intrinsically structurally unstable and may interact with the incident electron beam, constraining the electron beam density that can be used and the duration of the observation. Here we demonstrate that high-angle annular dark field (HAADF) in a spherical-aberration-corrected scanning transmission electron microscopy (STEM), coupled with imaging simulation, can be used to obtain a snapshot of the size, shape, orientation and atomic arrangement of size-selected metallic nanoclusters.