Bonding and vibrational dynamics of a largeπ-conjugated molecule on a metal surface

Abstract

The interplay between the substrate bonding of a largeπ-conjugated semiconductor molecule and the dynamical properties of the metal–organicinterface is studied, employing the prototypical PTCDA/Ag(111) monolayer as an example.Both the coupling of molecular vibrations to the electron–hole-pair continuum of themetal surface and the inelastic scattering of tunnelling electrons by the molecularvibrations on their passage through the molecule are considered. The results ofboth types of experiment are consistent with the findings of measurements whichprobe the geometric and electronic structure of the adsorbate–substrate complexdirectly; generally speaking, they can be understood in the framework of standardtheories for the electron–vibron coupling. While the experiments reported herein fact provide additional qualitative insights into the substrate bonding of ourπ-conjugated model molecule, their detailed quantitative understanding would require a fullcalculation of the dynamical interface properties, which is currently not available.