Article
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Electron-Phonon Coupling and Nonthermal Effects in Gold Nano-Objects at High Electronic Temperatures
Version 1
: Received: 25 May 2022 / Approved: 26 May 2022 / Online: 26 May 2022 (10:44:54 CEST)
A peer-reviewed article of this Preprint also exists.
Medvedev, N.; Milov, I. Electron–Phonon Coupling and Nonthermal Effects in Gold Nano-Objects at High Electronic Temperatures. Materials 2022, 15, 4883. Medvedev, N.; Milov, I. Electron–Phonon Coupling and Nonthermal Effects in Gold Nano-Objects at High Electronic Temperatures. Materials 2022, 15, 4883.
Abstract
Laser irradiation of metals is widely used in research and applications. In this work, we study how the material geometry affects electron-phonon coupling in nano-sized gold samples: an ultrathin layer, nano-rod, and two types of gold nanoparticles: cubic and octahedral. We use the combined tight-binding molecular dynamics Boltzmann collision integral method implemented within XTANT-3 code to evaluate the coupling parameter in irradiation targets at high electronic temperatures (up to Te~20,000 K). Our results show that the electron-phonon coupling in all objects with the same fcc atomic structure (bulk, layer, rod, cubic and octahedral nanoparticles) is nearly identical at electronic temperatures above Te~7000 K, independently of geometry and dimensionality. At low electronic temperatures, reducing dimensionality reduces the coupling parameter. Additionally, nano-objects under ultrafast energy deposition experience nonthermal damage due to expansion caused by electronic pressure, in contrast to bulk metal. Nano-object ultrafast expansion leads to ablation/emission of atoms, and disorder inside of the remaining parts. These nonthermal atomic expansion and melting are significantly faster than electron-phonon coupling, forming a dominant effect in nano-sized gold.
Keywords
Electron-phonon coupling; Nanoparticle; Ultrathin layer; Nonthermal melting; Tight-binding molecular dynamics; Boltzmann collision integrals; XTANT
Subject
Physical Sciences, Condensed Matter Physics
Copyright: This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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