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Ultrafast Heat Flow in Heterostructures of Au Nanoclusters on Thin Films: Atomic Disorder Induced by Hot Electrons

Thomas Vasileiadis, Lutz Waldecker, Dawn Foster, Alessandra Da Silva, Daniela Zahn, Roman Bertoni, Richard Palmer Orcid Logo, Ralph Ernstorfer

ACS Nano, Volume: 12, Issue: 8, Pages: 7710 - 7720

Swansea University Author: Richard Palmer Orcid Logo

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DOI (Published version): 10.1021/acsnano.8b01423

Abstract

We study the ultrafast structural dynamics, in response to electronic excitations, in heterostructures composed of size-selected Au nanoclusters on thin-film substrates with the use of femtosecond electron diffraction. Various forms of atomic motion, such as thermal vibrations, thermal expansion, an...

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Published in: ACS Nano
ISSN: 1936-0851 1936-086X
Published: 2018
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URI: https://cronfa.swan.ac.uk/Record/cronfa41123
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first_indexed 2018-07-25T13:34:39Z
last_indexed 2018-09-18T18:52:17Z
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spelling 2018-09-18T15:48:29.6914945 v2 41123 2018-07-25 Ultrafast Heat Flow in Heterostructures of Au Nanoclusters on Thin Films: Atomic Disorder Induced by Hot Electrons 6ae369618efc7424d9774377536ea519 0000-0001-8728-8083 Richard Palmer Richard Palmer true false 2018-07-25 MECH We study the ultrafast structural dynamics, in response to electronic excitations, in heterostructures composed of size-selected Au nanoclusters on thin-film substrates with the use of femtosecond electron diffraction. Various forms of atomic motion, such as thermal vibrations, thermal expansion, and lattice disordering, manifest as distinct and quantifiable reciprocal-space observables. In photoexcited supported nanoclusters, thermal equilibration proceeds through intrinsic heat flow between their electrons and their lattice and extrinsic heat flow between the nanoclusters and their substrate. For an in-depth understanding of this process, we have extended the two-temperature model to the case of 0D/2D heterostructures and used it to describe energy flow among the various subsystems, to quantify interfacial coupling constants and to elucidate the role of the optical and thermal substrate properties. When lattice heating of Au nanoclusters is dominated by intrinsic heat flow, a reversible disordering of atomic positions occurs, which is absent when heat is injected as hot substrate phonons. The present analysis indicates that hot electrons can distort the lattice of nanoclusters, even if the lattice temperature is below the equilibrium threshold for surface premelting. Based on simple considerations, the effect is interpreted as activation of surface diffusion due to modifications of the potential energy surface at high electronic temperatures. We discuss the implications of such a process in structural changes during surface chemical reactions. Journal Article ACS Nano 12 8 7710 7720 1936-0851 1936-086X Au nanoclusters; diffusion; electron−lattice interactions; expansion; hot electrons; nanoscale heat flow; premelting 31 12 2018 2018-12-31 10.1021/acsnano.8b01423 COLLEGE NANME Mechanical Engineering COLLEGE CODE MECH Swansea University 2018-09-18T15:48:29.6914945 2018-07-25T09:30:17.0780320 Faculty of Science and Engineering School of Aerospace, Civil, Electrical, General and Mechanical Engineering - Mechanical Engineering Thomas Vasileiadis 1 Lutz Waldecker 2 Dawn Foster 3 Alessandra Da Silva 4 Daniela Zahn 5 Roman Bertoni 6 Richard Palmer 0000-0001-8728-8083 7 Ralph Ernstorfer 8 0041123-25072018093215.pdf vasileiadis2018.pdf 2018-07-25T09:32:15.6700000 Output 2548390 application/pdf Accepted Manuscript true 2019-07-11T00:00:00.0000000 true eng
title Ultrafast Heat Flow in Heterostructures of Au Nanoclusters on Thin Films: Atomic Disorder Induced by Hot Electrons
spellingShingle Ultrafast Heat Flow in Heterostructures of Au Nanoclusters on Thin Films: Atomic Disorder Induced by Hot Electrons
Richard Palmer
title_short Ultrafast Heat Flow in Heterostructures of Au Nanoclusters on Thin Films: Atomic Disorder Induced by Hot Electrons
title_full Ultrafast Heat Flow in Heterostructures of Au Nanoclusters on Thin Films: Atomic Disorder Induced by Hot Electrons
title_fullStr Ultrafast Heat Flow in Heterostructures of Au Nanoclusters on Thin Films: Atomic Disorder Induced by Hot Electrons
title_full_unstemmed Ultrafast Heat Flow in Heterostructures of Au Nanoclusters on Thin Films: Atomic Disorder Induced by Hot Electrons
title_sort Ultrafast Heat Flow in Heterostructures of Au Nanoclusters on Thin Films: Atomic Disorder Induced by Hot Electrons
author_id_str_mv 6ae369618efc7424d9774377536ea519
author_id_fullname_str_mv 6ae369618efc7424d9774377536ea519_***_Richard Palmer
author Richard Palmer
author2 Thomas Vasileiadis
Lutz Waldecker
Dawn Foster
Alessandra Da Silva
Daniela Zahn
Roman Bertoni
Richard Palmer
Ralph Ernstorfer
format Journal article
container_title ACS Nano
container_volume 12
container_issue 8
container_start_page 7710
publishDate 2018
institution Swansea University
issn 1936-0851
1936-086X
doi_str_mv 10.1021/acsnano.8b01423
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Aerospace, Civil, Electrical, General and Mechanical Engineering - Mechanical Engineering{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Aerospace, Civil, Electrical, General and Mechanical Engineering - Mechanical Engineering
document_store_str 1
active_str 0
description We study the ultrafast structural dynamics, in response to electronic excitations, in heterostructures composed of size-selected Au nanoclusters on thin-film substrates with the use of femtosecond electron diffraction. Various forms of atomic motion, such as thermal vibrations, thermal expansion, and lattice disordering, manifest as distinct and quantifiable reciprocal-space observables. In photoexcited supported nanoclusters, thermal equilibration proceeds through intrinsic heat flow between their electrons and their lattice and extrinsic heat flow between the nanoclusters and their substrate. For an in-depth understanding of this process, we have extended the two-temperature model to the case of 0D/2D heterostructures and used it to describe energy flow among the various subsystems, to quantify interfacial coupling constants and to elucidate the role of the optical and thermal substrate properties. When lattice heating of Au nanoclusters is dominated by intrinsic heat flow, a reversible disordering of atomic positions occurs, which is absent when heat is injected as hot substrate phonons. The present analysis indicates that hot electrons can distort the lattice of nanoclusters, even if the lattice temperature is below the equilibrium threshold for surface premelting. Based on simple considerations, the effect is interpreted as activation of surface diffusion due to modifications of the potential energy surface at high electronic temperatures. We discuss the implications of such a process in structural changes during surface chemical reactions.
published_date 2018-12-31T03:52:25Z
_version_ 1763752590113243136
score 11.013641

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