Research Repository

# Resonant core spectroscopies of the charge transfer interactions between C60 and the surfaces of Au(111), Ag(111), Cu(111) and Pt(111)

## Authors

Andrew J. Gibson

Robert H. Temperton Robert.Temperton@nottingham.ac.uk

James N. O'Shea

Karsten Handrup

### Abstract

Charge transfer interactions between C60 and the metal surfaces of Ag(111), Cu(111), Au(111) and Pt(111) have been studied using synchrotron-based photoemission, resonant photoemission and X-ray absorption spectroscopies. By placing the X-ray absorption and valence band spectra on a common binding energy scale, the energetic overlap of the unoccupied molecular orbitals with the density of states of the underlying metal surface have been assessed in the context of possible charge transfer pathways. Resonant photoemission and resonant Auger data, measuring the valence region as a function of photon energy for C60 adsorbed on Au(111) reveals three constant high kinetic energy features associated with Auger-like core-hole decay involving an electron transferred from the surface to the LUMO of the molecule and electrons from the three highest occupied molecular orbitals, respectively and in the presence of ultra-fast charge transfer of the originally photoexcited molecule to the surface. Data for the C60/Ag(111) surface reveals an additional Auger-like feature arising from a core-hole decay process involving more than one electron transferred from the surface into the LUMO. An analysis of the relative abundance of these core-hole decay channels estimates that on average 2.4 $\pm$ 0.3 electrons are transferred from the Ag(111) surface into the LUMO. A core-hole clock analysis has also been applied to assess the charge transfer coupling in the other direction, from the molecule to the Au(111) and Ag(111) surfaces. Resonant photoemission and resonant Auger data for C60 molecules adsorbed on the Pt(111) and Cu(111) surfaces are shown to exhibit no super-Auger features, which is attributed to the strong modification of the unoccupied molecular orbitals arising from stronger chemical coupling of the molecule to the surface.

Journal Article Type Article Mar 1, 2017 Surface Science 0039-6028 0039-6028 Elsevier Peer Reviewed 657 Gibson, A. J., Temperton, R. H., O'Shea, J. N., & Handrup, K. (2017). Resonant core spectroscopies of the charge transfer interactions between C60 and the surfaces of Au(111), Ag(111), Cu(111) and Pt(111). Surface Science, 657, doi:10.1016/j.susc.2016.11.009 https://doi.org/10.1016/j.susc.2016.11.009 fullerenes, metal surfaces, charge transfer, resonant photoemission, core-hole clock, autoionization http://www.sciencedirect.com/science/article/pii/S0039602816304940 Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by-nd/4.0

C60.pdf (835 Kb)
PDF