Electron-Vibron Coupling at Metal-Organic Interfaces from Theory and Experiment

TL;DR

This study combines experimental and theoretical methods to analyze electron-vibron coupling at metal-organic interfaces, revealing the dominant role of interfacial dynamical charge transfer in infrared activity.

Contribution

It provides a quantitative analysis of interfacial dynamical charge transfer and its impact on infrared activity using combined spectroscopy and density functional theory.

Findings

Interfacial dynamical charge transfer is the main cause of infrared activity.

Nuclear motion contributes minimally to dynamic dipole moments.

Results correlate partial charge analysis with density of states.

Abstract

We study the significance and characteristics of interfacial dynamical charge transfer at metal-organic interfaces for the organic semiconductor model system 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTCDA) on Ag(111) quantitatively. We combine infrared absorption spectroscopy and dispersion-corrected density functional theory calculations to analyze dynamic dipole moments and electron-vibron coupling at the interface. We demonstrate that interfacial dynamical charge transfer is the dominant cause of infrared activity in these systems and that it correlates with results from partial charge and density of states analysis. Nuclear motion generates an additional dynamic dipole moment but represents a minor effect except for modes with significant out-of-plane amplitudes.