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Title: Enhanced generation and anisotropic Coulomb scattering of hot electrons in an ultra-broadband plasmonic nanopatch metasurface

The creation of energetic electrons through plasmon excitation of nanostructures before thermalization has been proposed for a wide number of applications in optical energy conversion and ultrafast nanophotonics. However, the use of "nonthermal" electrons is primarily limited by both a low generation efficiency and their ultrafast decay. We report experimental and theoretical results on the use of broadband plasmonic nanopatch metasurfaces comprising a gold substrate coupled to silver nanocubes that produce large concentrations of hot electrons, which we measure using transient absorption spectroscopy. We find evidence for three subpopulations of nonthermal carriers which we propose arise from anisotropic electron-electron scattering within sp-bands near the Fermi surface. The bimetallic character of the metasurface strongly impacts the physics, with dissipation occurring primarily in the gold whereas the quantum process of hot electron generation takes place in both components. As a result, our calculations show that the choice of geometry and materials is crucial for producing strong ultrafast nonthermal electron components.
Authors:
 [1] ; ORCiD logo [2] ;  [2] ; ORCiD logo [3] ;  [4] ;  [1] ; ORCiD logo [1] ;  [1] ; ORCiD logo [2] ; ORCiD logo [5] ;  [1]
  1. Argonne National Lab. (ANL), Argonne, IL (United States)
  2. Duke Univ., Durham, NC (United States)
  3. Univ. of Electronic Science and Technology of China, Chengdu (China); Ohio Univ., Athens, OH (United States)
  4. Univ. of Electronic Science and Technology of China, Chengdu (China)
  5. Ohio Univ., Athens, OH (United States)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 8; Journal Issue: 1; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
Air Force Research Laboratory (AFRL), Air Force Office of Scientific Research (AFOSR); US Army Research Office (ARO); USDOE Office of Science (SC), Energy Frontier Research Center; Argonne-Northwestern Solar Energy Research (ANSER); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22), Scientific User Facilities Division
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY
OSTI Identifier:
1402469