Energy-Resolved Femtosecond Hot Electron Dynamics in Single Plasmonic Nanoparticles
Résumé
Efficient excitation and harvesting of hot carriers from nanoscale metals is central to many emerging photochemical, photovoltaic, andultrafast optoelectronic applications. Nevertheless, direct experimental evidence of the energy-dependent femtosecond dynamics in ubiquitous tens-of-nanometer gold structures remains elusive, despite the potentially rich interplay between interfacial and internal plasmonic fields,excitation distributions, and scattering processes. To explore the effects of nanoscale structure on these dynamics, we employ simultaneous time-, angle-, and energy-resolved photoemission spectroscopy of single plasmonic nanoparticles. Photoelectron velocity and electric field distributions reveal bulk-like ballistic hot electron transport indifferent geometries, lacking any signatures of surface effects. Energy-resolved dynamics are measured in the 1-2 eV range and extrapolated to lower energies via Boltzmann theory, providing a detailed viewof hot electron lifetimes within nanoscale gold. We find that particles with relevant dimensions as small as 10 nm serve as exemplary platforms for studying intrinsic metal dynamics.
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