Electron-Phonon Coupling and Nonthermal Effects in Gold Nano-Objects at High Electronic Temperatures

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Laser-induced effects on metals are crucial for research and applications.
• Understanding electron-phonon coupling is key to predicting material behavior under irradiation.
• Nanomaterials exhibit unique properties compared to their bulk counterparts.

Purpose of the Study:

• Investigate the influence of material geometry on electron-phonon coupling in nano-sized gold.
• Evaluate electron-phonon coupling parameters at high electronic temperatures.
• Analyze nonthermal damage mechanisms in gold nanostructures under ultrafast laser irradiation.

Main Methods:

• Utilized the tight-binding molecular dynamics Boltzmann collision integral method.
• Implemented the simulation within the XTANT-3 code.
• Studied various gold nanostructures: ultrathin layer, nano-rod, cubic, and octahedral nanoparticles.

Main Results:

• Electron-phonon coupling in gold nanostructures with fcc structure is nearly identical above 7000 K, irrespective of geometry.
• Reduced dimensionality leads to decreased electron-phonon coupling at lower electronic temperatures.
• Ultrafast laser energy deposition causes nonthermal damage via electronic pressure-induced expansion in nano-objects.

Conclusions:

• Geometry-independent electron-phonon coupling in gold nanostructures at high temperatures.
• Nonthermal atomic expansion and melting are dominant damage mechanisms in nano-sized gold, preceding electron-phonon coupling.
• Findings are critical for designing laser-based nanomaterial processing and understanding laser-matter interactions at the nanoscale.