Pyridine as a Resonantly Addressable Group to Study Electron-Transfer Dynamics in Self-Assembled Monolayers

Abstract

Resonant Auger electron spectroscopy (RAES) in combination with the core-hole clock (CHC) approach represents a unique tool to study femtosecond electron transfer (ET) dynamics in molecular systems and self-assembled monolayers (SAMs) in particular. A most promising experimental strategy to apply this approach to SAMs involves the decoration of the target films with a group, which can be resonantly excited by narrow-band X-rays. Using a series of well-defined SAMs with a terminal pyridine moiety, we demonstrate here that pyridine can be used as such a group, as an alternative to the nitrile group, which has been utilized for this purpose in the past. For these SAMs, we evaluate the characteristic time for ET from the terminal nitrogen atom of the pyridine group through the molecular framework to the substrate and discuss the results in terms of conjugation and coupling of the relevant electronic states in the molecules. The obtained ET times correlate well with the literature values obtained for the analo...