Direct Experimental Evidence for the Hybridization of Organic Molecular Orbitals with Substrate States at Interfaces: PTCDA on Silver

TL;DR

This study uses orbital k-space tomography via ARPES to directly demonstrate the hybridization of organic molecular orbitals with substrate states at metal-organic interfaces, specifically for PTCDA on silver surfaces.

Contribution

It introduces a novel application of orbital k-space tomography to directly observe and quantify orbital hybridization at metal-organic interfaces.

Findings

Confirmed hybridization of PTCDA orbitals with silver substrate states

Quantified substrate contribution to the LUMO

Proved the hybrid character of the complex state

Abstract

We demonstrate the application of orbital k-space tomography for the analysis of the bonding occurring at metal-organic interfaces. Using angle-resolved photoelectron spectroscopy (ARPES), we probe the spatial structure of the highest occupied molecular orbital (HOMO) and the former lowest unoccupied molecular orbital (LUMO) of one monolayer 3,4,9,10-perylenetetracarboxylic-dianhydride (PTCDA) on Ag(110) and (111) surfaces and in particular the influence of the hybridization between the orbitals and the electronic states of the substrate. We are able to quantify and localize the substrate contribution to the LUMO and thus prove the metal-molecule hybrid character of this complex state.