Thema der Dissertation:
Ultrafast Photodynamics in Catalytic Molecular Compounds Studied by Femtosecond Time-Resolved EUV Photoemission and UV-Vis Absorption Spectroscopy
Ultrafast Photodynamics in Catalytic Molecular Compounds Studied by Femtosecond Time-Resolved EUV Photoemission and UV-Vis Absorption Spectroscopy
Abstract: These studies address the fundamentals of ultrafast photophysical processes, in particular, electronic dynamics in catalytic molecular systems. In this work, the ultrafast photodynamics of two different homogeneous and heterogeneous catalysts were investigated: the ferricyanide ([Fe(CN)6]3-) transition metal complex dissolved in the ionic liquid [emim][DCA] and polymeric carbon nitride (PCN) thin films. The femtosecond time-resolved photoemission spectroscopy (TRPES) was employed as the main spectroscopic tool to interrogate both systems on their fundamental time scales, employing tunable, extreme-ultraviolet (EUV), ultrashort probe pulses, as generated through the laser-driven high-order harmonic generation process. To examine the photoinduced electron dynamics in different PCN thin films upon 400 nm excitation at the solid-vacuum interface, combined femtosecond TRPES and ultraviolet-visible (UV-Vis) transient absorption spectroscopy (TAS) studies were performed. The sensitivity of the TRPES technique to both electronic structure and electronic dynamics allowed the determination of individual contributions from specific electronic states of a photoexcited catalytically-active molecular system on an absolute binding energy scale with high accuracy. The TAS technique gave insights into photogenerated excited state absorption energies and high-resolution kinetic profiles of the transient species formation and decay. This work has shown that, by combining EUV-based TRPES and UV-Vis TAS studies, the kinetic and spectral information about electronic dynamic processes occurring at different stages of the photophysical pathway in catalytic molecular compounds can be accessed. The application of such information provides the means to correlate light-harvesting mechanisms and photophysicochemical behaviour of catalytically-active systems with electron and energy transfer processes, contributing to further optimisation and development of highly-efficient selective functional materials.
Zeit & Ort
14.07.2023 | 10:00
Hörsaal A (1.3.14)
Fachbereich Physik, Arnimallee 14, 14195 Berlin