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

0579465 - ÚFP 2024 RIV CH eng J - Journal Article
Medvedev, Nikita - Milov, I.
Electron–Phonon Coupling and Nonthermal Effects in Gold Nano-Objects at High Electronic Temperatures.
Materials. Roč. 15, č. 14 (2022), č. článku 4883. E-ISSN 1996-1944
Grant - others:Ministerstvo školství, mládeže a tělovýchovy - GA MŠk(CZ) LM2018140; European Cooperation in Science and Technology(BE) CA17126
Program: COST
Institutional support: RVO:61389021
Keywords : Boltzmann collision integrals * electron–phonon coupling * nanoparticle * nonthermal melting * tight-binding molecular dynamics * ultrathin layer * xtant
OECD category: Optics (including laser optics and quantum optics)
Impact factor: 3.4, year: 2022
Method of publishing: Open access
https://www.mdpi.com/1996-1944/15/14/4883

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 the ablation/emission of atoms and disorders the 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.
Permanent Link: https://hdl.handle.net/11104/0348302