Erlangen 2018 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 3: Photoelectron Spectroscopy

MO 3.1: Hauptvortrag

Montag, 5. März 2018, 10:30–11:00, PA 2.150

Electronic structure and relaxation of solvated organic molecules studied by time-resolved photoelectron spectroscopy — Johan Hummert, Geert Reitsma, Nicola Mayer, Evgenii Ikonnikov, Martin Eckstein, and •Oleg Kornilov — Max Born Institute, Berlin, Germany

Photoactive processes play a role in many biological systems from human vision to light harvesting. Electronic relaxation and structural rearrangements following photon absorption often strongly depend on the chromophore environment. These dynamics are extensively studied by all-optical techniques, but the tools of time-resolved photoelectron spectroscopy (TRPES), which brought many insights in gas phase and in solid state physics, have not been applied until recently. In this contribution we demonstrate TRPES of organic molecules in aqueous solutions combining monochromatized femtosecond XUV pulses [1] and the microliquid jet technology. We analyze electronic structure of several organic molecules and follow relaxation dynamics of one of them, Quinoline Yellow. Quinoline Yellow in a non-polar aprotic solvent was recently suggested to undergo an excited state proton transfer (ESPT) from a nitrogen to an oxygen atom [2]. Relaxation timescales obtained in our experiment are consistent with this proposal, but the process seems to be faster in water. Additionally, our results indicate an ultrafast solvent rearrangement following a significant change of molecular dipole upon electronic excitation. [1] M. Eckstein et al, Phys. Rev. Lett. 116, 163003 (2016) [2] G. R. Han et al, Sci. Reports, 7, 3863 (2017)