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Nguyen QLD, Simoni J, Dorney KM, Shi X, Ellis JL, Brooks NJ, Hickstein DD, Grennell AG, Yazdi S, Campbell EEB, Tan LZ, Prendergast D, Daligault J, Kapteyn HC, Murnane MM. Direct Observation of Enhanced Electron-Phonon Coupling in Copper Nanoparticles in the Warm-Dense Matter Regime. Phys Rev Lett 2023; 131:085101. [PMID: 37683150 DOI: 10.1103/physrevlett.131.085101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 06/27/2022] [Accepted: 05/26/2023] [Indexed: 09/10/2023]
Abstract
Warm dense matter (WDM) represents a highly excited state that lies at the intersection of solids, plasmas, and liquids and that cannot be described by equilibrium theories. The transient nature of this state when created in a laboratory, as well as the difficulties in probing the strongly coupled interactions between the electrons and the ions, make it challenging to develop a complete understanding of matter in this regime. In this work, by exciting isolated ∼8 nm copper nanoparticles with a femtosecond laser below the ablation threshold, we create uniformly excited WDM. Using photoelectron spectroscopy, we measure the instantaneous electron temperature and extract the electron-ion coupling of the nanoparticle as it undergoes a solid-to-WDM phase transition. By comparing with state-of-the-art theories, we confirm that the superheated nanoparticles lie at the boundary between hot solids and plasmas, with associated strong electron-ion coupling. This is evidenced both by a fast energy loss of electrons to ions, and a strong modulation of the electron temperature induced by strong acoustic breathing modes that change the nanoparticle volume. This work demonstrates a new route for experimental exploration of the exotic properties of WDM.
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Affiliation(s)
- Quynh L D Nguyen
- JILA, Department of Physics, University of Colorado and NIST, Boulder, Colorado 80309, USA
| | - Jacopo Simoni
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Kevin M Dorney
- JILA, Department of Physics, University of Colorado and NIST, Boulder, Colorado 80309, USA
| | - Xun Shi
- JILA, Department of Physics, University of Colorado and NIST, Boulder, Colorado 80309, USA
| | - Jennifer L Ellis
- JILA, Department of Physics, University of Colorado and NIST, Boulder, Colorado 80309, USA
| | - Nathan J Brooks
- JILA, Department of Physics, University of Colorado and NIST, Boulder, Colorado 80309, USA
| | - Daniel D Hickstein
- Kapteyn-Murnane Laboratories Inc., 4775 Walnut St #102, Boulder, Colorado 80301, USA
| | - Amanda G Grennell
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309 80309, USA
| | - Sadegh Yazdi
- Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, Colorado 80309, USA
| | - Eleanor E B Campbell
- EaStCHEM, School of Chemistry, Edinburgh University, David Brewster Road, Edinburgh EH9 3FJ, United Kingdom
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Liang Z Tan
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - David Prendergast
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Jerome Daligault
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Henry C Kapteyn
- JILA, Department of Physics, University of Colorado and NIST, Boulder, Colorado 80309, USA
- Kapteyn-Murnane Laboratories Inc., 4775 Walnut St #102, Boulder, Colorado 80301, USA
| | - Margaret M Murnane
- JILA, Department of Physics, University of Colorado and NIST, Boulder, Colorado 80309, USA
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