Dynamics of photoinduced resonant energy transfer characterized at the single molecule level.

Projektbeschreibung

Innovatives Experiment beleuchtet Energietransfer auf Nanoebene

Photonen sind die elementaren Einheiten bzw. Quanten des Lichts. Jedes Photon hat eine bestimmte Energie und die Energieübertragung mit Photonen von einer Quelle zu einem Empfänger ist das Herzstück von Photosynthese, Photokatalyse und Optoelektronik. Zwar konnten die spektroskopischen und zeitlichen Eigenschaften dieses Prozesses bereits gut abgebildet werden, doch die räumliche Auflösung bei Weitem nicht. Um die Prozesse der Energieübertragung steuern und Technik mit wachsender Komplexität, Effizienz und Funktionalität konstruieren zu können, muss die Wissenschaft mehr über die Energieübertragung herausfinden, die auf Nanoebene zwischen den Quellen und ihren Empfängern abläuft. Genau das soll im EU-finanzierten Projekt PRETZEL mit einem neu entwickelten experimentellen Ansatz gelingen, der ein grundlegendes Verständnis von Energieübertragung auf atomarer Ebene sowie technologische Innovationen ermöglicht.

Ziel

Energy transfer constitutes a basic step of photosynthesis, photocatalysis and operation of optoelectronic devices in which the energy of a photon absorbed by one entity (donor) is transferred to another entity (acceptor) where it is further processed. The fundamentals of this process are routinely studied using optical-based methods, which are sensitive to its spectroscopic and temporal characteristics. However, these techniques are diffraction-limited, leading to spatial averaging of the fine details occurring at the molecular scale, and do not allow to study how energy transfer and its dynamics are affected by minute change variations of the atomic-scale environment of the donor-acceptor pair.
Therefore, crucial questions remain to be addressed: Can we probe and control ET as a function of the precise nanometre distances and orientation of the single donor-acceptor pairs? What is the nanometre-scale interplay between different ET mechanisms? How are the dynamics, and thus the efficiency, of ET affected by these parameters? Can we probe more complex behaviours involving ET or mimic light-harvesting systems based on artificial supramolecular architectures?
To reach the required scale a novel approach will be developed that combines the atomic-scale precision of a low-temperature scanning tunnelling microscopy with time-resolved tip-enhanced photoluminescence. This original technical association will enable studies of energy transfer dynamics between individual molecules with simultaneous pm and ps at the unprecedented scale. The fundamental knowledge gained during the project, as well as technological development, will lead to a better understanding of the atomic-scale phenomena driving photosynthesis and optoelectronic devices operations. Furthermore, PRETZEL will offer extensive interdisciplinary training for a young researcher, creating the base for a highly successful scientific career.