Investigation of Nonequilibrium Electronic Dynamics of Warm Dense Copper with Femtosecond X-Ray Absorption Spectroscopy

Jong-Won Lee, Minju Kim, Gyeongbo Kang, Sam M. Vinko, Leejin Bae, Min Sang Cho, Hyun-Kyung Chung, Minseok Kim, Soonnam Kwon, Gyusang Lee, Chang Hee Nam, Sang Han Park, Jang Hyeob Sohn, Seong Hyeok Yang, Ulf Zastrau, and Byoung Ick Cho
Phys. Rev. Lett. 127, 175003 – Published 22 October 2021

Abstract

Ultrafast optical excitation of matter leads to highly excited states that are far from equilibrium. In this study, femtosecond x-ray absorption spectroscopy was used to visualize the ultrafast dynamics in photoexcited warm dense Cu. The rich dynamical features related to d vacancies are observed on femtosecond timescales. Despite the success in explaining x-ray absorption data in the picosecond regime, the new femtosecond data are poorly understood through the traditional two-temperature model based on the fast thermalization concept and the static electronic structure for high-temperature metals. An improved understanding can be achieved by including the recombination dynamics of nonthermal electrons and changes in the screening of the excited d block. The population balance between the 4sp and 3d bands is mainly determined by the recombination rate of nonthermal electrons, and the underpopulated 3d block is initially strongly downshifted and recovered in several hundreds of femtoseconds.

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  • Received 1 June 2021
  • Revised 11 August 2021
  • Accepted 23 September 2021

DOI:https://doi.org/10.1103/PhysRevLett.127.175003

© 2021 American Physical Society

Physics Subject Headings (PhySH)

Plasma Physics

Authors & Affiliations

Jong-Won Lee1,2,†,‡, Minju Kim1,2,†, Gyeongbo Kang1,2, Sam M. Vinko3,4, Leejin Bae5, Min Sang Cho1,2, Hyun-Kyung Chung6, Minseok Kim7, Soonnam Kwon7, Gyusang Lee1,2, Chang Hee Nam1,2, Sang Han Park7, Jang Hyeob Sohn2, Seong Hyeok Yang2, Ulf Zastrau8, and Byoung Ick Cho1,2,*

  • 1Center for Relativistic Laser Science, Institute for Basic Science, Gwangju 61005, Republic of Korea
  • 2Department of Physics and Photon Science, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea
  • 3Department of Physics, University of Oxford, Parks Road, Oxford OXI 3PU, United Kingdom
  • 4Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom
  • 5Korea Atomic Energy Research Institute, Daejeon 34057, Republic of Korea
  • 6Korea Institute of Fusion Energy, Daejeon 34133, Republic of Korea
  • 7Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, Republic of Korea
  • 8European XFEL Gmbh, Notkestrasse 85, D-22607 Hamburg, Germany

  • *Corresponding author. bicho@gist.ac.kr
  • These authors contributed equally to this work.
  • Present address: Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, Republic of Korea.

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Issue

Vol. 127, Iss. 17 — 22 October 2021

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