Abstract
Hot-electron dynamics at metal surfaces are crucial for charge transport properties and chemical reactions at metal/organic interfaces. In order to study the influence of electron-donating adsorbates on hot-electron lifetimes we performed femtosecond time-resolved two-photon photoemission measurements of tetrathiafulvalene (TTF)-covered Au(111) surfaces. The electron-donating nature of TTF provides density of states near the Fermi energy () increasing the possibility for electron-electron scattering events. This leads to an additional fast electron-electron scattering assisted hot-electron relaxation channel for low intermediate state energies () at the TTF/Au(111) interface with hot-electron lifetimes up to . However, suppressing the electron donation via intercalation of electron-accepting tetracyanoquinodimethane molecules causes quenching of this fast electron relaxation channel. This results in an asymptotic increase of the hot-electron lifetimes for infinitesimal small intermediate state energies up to about as predicted by the pure Landau theory of Fermi liquids.
- Received 13 June 2017
- Revised 21 September 2017
DOI:https://doi.org/10.1103/PhysRevB.96.144304
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