Adsorption-induced modification of the hot electron lifetime in a Pb/Ag111 quantum well system

TL;DR

This study investigates how adsorbing PTCDA molecules on a Pb/Ag(111) quantum well system alters electron lifetimes and scattering processes, revealing a method to control ultrafast charge dynamics at interfaces.

Contribution

It demonstrates that organic molecule adsorption can selectively modify interband scattering, providing a new way to tune quantum well electron dynamics.

Findings

Adsorption suppresses interband scattering in the quantum well system.

Electron dynamics become dominated by intraband and inelastic scattering after adsorption.

Organic molecules can be used to control scattering processes in quantum well systems.

Abstract

The interfacial band structures of multilayer systems play a crucial role for the ultrafast charge and spin carrier dynamics at interfaces. Here, we study the energy- and momentum-dependent quasiparticle lifetimes of excited states of a lead monolayer film on Ag(111) prior and after the adsorption of a monolayer of 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA). Using time-resolved two-photon momentum microscopy, we show that the electron dynamics of the bare Pb/Ag(111) bilayer system is dominated by isotropic intraband scattering processes within the quantum well state as well as interband scattering processes from the QWS into the Pb sideband. After the adsorption of PTCDA on the Pb monolayer, the interband scattering is suppressed and the electron dynamics is solely determined by intraband or inelastic scattering processes. Our findings hence uncover a new possibility to selectively tune and control scattering processes of quantum well systems by the adsorption of organic molecules.