Post-doc in femtosecond XPS of bio-mimetic photoswitches (H/F)

Within a joint collaboration of the above partner labs, the post-doc position is located in both ultrafast spectroscopy labs in Strasbourg (IPCMS) and at MBI, Berlin. The Strasbourg team has a long-standing experience with these particular, vibrationally coherent photo-switches , studied by broadband UV/VIS TAS with sub-10fs resolution . The team of Dr. O. Kornilov at MBI runs a state-of-the-art femtosecond UV-pump-HHG/XUPS-probe experiment with liquid jets . In recent experiments, the ground state XUPS spectra of the photo-switches were obtained, for both anionic and cationic forms with high photo-emission yield. The first pump-probe experiments are in progress at MBI.
The post-doc will complete the first proof-of-principle phase on well-characterised molecules, in Berlin, before the project is extended to new complexes aimed at studying the influence of vibrational coherence and chemical substitutions on the isomerisation quantum yield and dynamics at the CInt. This second phase implies experiments both in Strasbourg and Berlin, relying on the above set-ups. Theoretical support will be provided by Prof. M. Olivucci (U Siena & Bowling Green), inventor of the photo-switches, and Dr. S. Gozem (GSU Atlanta). Photo-switches will be designed for this project and provided in sufficient amount by chemistry partners. Some of them are commercially available.

Rhodopsins are the protein photo-receptors for vision in vertebrates. Microbial organisms use them, too, but for other forms of photo-sensing or for primitive photosynthesis. From a molecular point of view, the start for these processes is photo-isomerisation: light converts the chromophore retinal from its cis to the trans form, a photo-chemical process, which occurs within a few hundreds of femtoseconds and with > 50% quantum efficiency.
Photo-isomerisation implies large molecular motion, out-of-plane bond twists and rotation around C-C bonds of retinal. Quantum mechanically, the transition from cis to trans occurs when these motions make the electronic excited and ground states degenerate, at the so-called conical intersections (CInt). Quantum chemistry has predicted these transition states to be the decisive states determining the quantum efficiency of the reaction, but CInt's have so far escaped from direct observation in standard UV/VIS/mid-IR pump-probe transient absorption experiments.
In this joint collaboration between the Max-Born-Institute, Berlin (Dr. O. Kornilov) and the IPCMS Strasbourg (Dr. J. Léonard & Prof. S. Haacke), we bring together our expertise to investigate the CInt of rhodopsin-mimicking photo-switches using novel tools of femtosecond and attosecond XUV photoelectron spectroscopy (XUPS).

The Strasbourg Insititute of Physics and Chemistry of Materials (IPCMS) is the host institute where standard femtosecond spectroscopy experiments in the UV/VIS domain are performed. The post-doc will be sent on extended missions (several months) to the MBI partner lab in Berlin. Here the main tasks is to perform femtosecond XPS experiments in liquid jets, which is the main novelty of the project.