Mechanisms of radiation-induced structural transformations in deposited gold clusters

Abstract

Physical mechanisms of structural transformations in deposited metallic clusters exposed to an electron beam of a transmission electron microscope (TEM) are studied theoretically and computationally. Recent TEM experiments with size-selected Au${}_{923}$ clusters softly deposited on a carbon substrate showed that the clusters undergo structural transformations from icosahedron to decahedron and face-center cubic (fcc) structures upon exposure to a 200-keV electron beam. In this paper, we demonstrate that the relaxation of collective electronic (plasmon) excitations formed in deposited metal clusters can induce the experimentally observed structural transformations. Such excitations in the clusters are formed mainly due to the interaction with low-energy secondary electrons emitted from a substrate. The characteristic occurrence times for plasmon-induced energy relaxation events are several orders of magnitude shorter than those for the momentum transfer events by energetic primary electrons to atoms of the cluster. The theoretical analysis is complemented by molecular dynamics simulations, which show that an icosahedral Au${}_{923}$ cluster softly deposited on graphite is transformed into an fcc-like structure due to the vibrational excitation of the cluster.

arXiv comment14 pages, 10 figures

References in corpus (10)

• Structure identification methods for atomistic simulations of crystalline materials
• Optical excitations in electron microscopy
• Quantifying transmission electron microscopy irradiation effects using two-dimensional materials
• Generation of Traveling Surface Plasmon Waves by Free-Electron Impact
• Excitation and relaxation in atom-cluster collisions
• Revealing the Mechanism of Low-Energy Electron Yield Enhancement from Sensitizing Nanoparticles
• Electron production by sensitizing gold nanoparticles irradiated by fast ions
• Fast electronic relaxation in metal nanoclusters via excitation of coherent shape deformations: Circumventing a bottleneck
• Excitation of surface and volume plasmons in metal nanocluster by fast electrons
• Soft landing of metal clusters on graphite: a molecular dynamics study

Cited by in corpus (2)

• Condensed Matter Systems Exposed to Radiation: Multiscale Theory, Simulations, and Experiment
• Dynamics of single Au nanoparticles on graphene simultaneously in real- and diffraction space by time-series convergent beam electron diffraction