Upper Bound Estimate of the Electronic Scattering Potential of a Weakly Interacting Molecular Film on a Metal

TL;DR

This study estimates the maximum scattering potential of a weakly interacting molecular film on a metal surface by analyzing 2D electronic states, providing a method to quantify electronic interactions at hybrid interfaces.

Contribution

The paper introduces a perturbative approach to upper bound the scattering potential at organic/inorganic interfaces using FT-STS data.

Findings

2D electronic states are free-electron-like near the Gamma-point.

The scattering potential amplitude is estimated to be around 1.5 eV.

The method quantifies weak electronic interactions at hybrid 2D interfaces.

Abstract

Thin organic films and two-dimensional (2D) molecular assemblies on solid surfaces yield the potential for applications in molecular electronics, optoelectronics, catalysis, and sensing. These applications rely on the intrinsic electronic properties of the hybrid organic/inorganic interface. Here, we investigate the energy dispersion of 2D electronic states at the interface between an atomically thin self-assembled molecular film, comprised of flat, noncovalently bonded 9,10-dicyanoanthracene (DCA) molecules, and a Ag(111) surface. Using Fourier-transformed scanning tunnelling spectroscopy (FT-STS), we determined that the 2D electronic wave functions with wavevectors within ~80% of the first Brillouin zone (BZ) area close to the Gamma-point are free-electron-like, suggesting a weak electronic interaction between the 2D molecular film and the metal surface. Via a perturbative second-order correction to the free electron energy dispersion, we further established an upper bound for the amplitude of the scattering potential resulting from the self-assembled molecular film that the interface electrons are subject to, on the order of 1.5 eV. Our approach allows for quantifying electronic interactions at hybrid 2D interfaces and heterostructures.