Charge transfer dynamics in molecular solids and adsorbates driven by local and non-local excitations

Abstract

Charge transfer pathways and charge transfer times in molecular films and in adsorbate layers depend both on the details of the electronic structure as well as on the degree of the initial localization of the propagating excited electronic state. For C6F6 molecular adsorbate films on the Cu(111) surface we determined the interplay between excited state localization and charge transfer pathways. In particular we selectively prepared a free-particle-like LUMO band excitation and compared it to a molecularly localized core-excited C1s→π⁎ C6F6 LUMO state using time-resolved two-photon photoemission (tr-2PPE) and core–hole–clock (CHC) spectroscopy, respectively. For the molecularly localized core-excited C1s→π⁎ C6F6 LUMO state, we separate the intramolecular dynamics from the charge transfer dynamics to the metal substrate by taking the intramolecular dynamics of the free C6F6 molecule into account. Our analysis yields a generally applicable description of charge transfer within molecular adsorbates and to the substrate.