Atomistic modelling of electron beam induced structural transformations in deposited metal clusters

Area of Science:

• Materials Science
• Nanotechnology
• Computational Physics

Background:

• Investigating nanoscale material behavior under external stimuli is crucial for developing advanced applications.
• Understanding electron-matter interactions at the atomic level informs material design and processing.
• Gold clusters offer unique electronic and catalytic properties, making them relevant for various technological fields.

Purpose of the Study:

• To investigate the structural transformations of gold clusters induced by electron beam irradiation.
• To elucidate the mechanisms of energy transfer from a 300 keV electron beam to gold clusters on graphite.
• To simulate the dynamics and thermal behavior of gold clusters during and after irradiation.

Main Methods:

• Classical molecular dynamics (MD) simulations using the MBN Explorer software package.
• Relativistic MD approach to model primary electron-cluster atom collisions.
• Simulation of two primary energy transfer mechanisms: electronic excitation relaxation and momentum transfer.
• Analysis of cluster dynamics, temperature evolution, and structural changes post-irradiation.

Main Results:

• Identified two primary energy transfer pathways during electron beam irradiation.
• Simulated rapid cooling of the gold cluster within picoseconds, followed by slower cooling.
• Demonstrated that cumulative energy deposition from numerous events can lead to significant cluster heating.
• Observed that sustained irradiation can induce substantial structural transformations in the gold clusters.

Conclusions:

• Electron beam irradiation can induce significant structural transformations in gold clusters.
• The interplay between energy deposition events and cooling dynamics dictates the overall thermal response.
• MD simulations provide valuable insights into the complex dynamics of nanomaterials under irradiation, guiding experimental design.