Erlangen 2018 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 3: Photoelectron Spectroscopy

MO 3.2: Vortrag

Montag, 5. März 2018, 11:00–11:15, PA 2.150

A ps time-resolved photoelectron imaging study on the photophysics of Acenaphthylene — •Marco Flock, Max Herbert, and Ingo Fischer — Institute of Physical and Theoretical Chemistry, Julius Maximilians University of Wuerzburg, Germany

Acenaphthylene is a member of the chemical group of polycyclic aromatic hydrocarbons (PAHs). PAHs are a toxic and cancerogen species and are emitted to the environment mainly through incomplete combustion processes. Thus, they are supposed to significantly increase the risk of human cancer diseases. Beside their toxicology, PAHs show interesting photophysical properties and are promising building blocks for devices like semiconductors or solar cells. In our studies, we investigated the excited state dynamics of the S1 and S2 state of Acenaphthylene. Time-resolved TOF photoionization and photoelectron imaging experiments showed an IC transition from the S1 state to the ground state with decreasing lifetimes from 480 ps at the S1 origin to 100 ps at a vibronic excess energy of 2700 cm-1. In further experiments, a monoexponential decay after excitation of the S2 state was detected. This can be explained by a very fast IC transition to the high vibronically excited S1 state, followed by another IC to the electronic ground state. The time constant of this second process further decreases to a value of around 55 ps. Besides, time resolved photoelectron images show a constant signal offset at long delay times, which indicates a competing ISC transition to the triplet manifold after S2 excitation.