Photoinduced electron transfer reactions in molecular donor-acceptor systems involve charge transfer over extended distances. Our research on the elementary steps of photoinduced charge transfer in bimolecular electron transfer in donor-acceptor pairs has its foundations made in a larger set of activities on photo-induced elementary reactions followed with ultrafast infrared spectroscopy. Recent progress has been made at the MBI to construct a table-top high-order harmonic set-up producing ultrashort soft-x-ray pulses extending well into the water window spectral range. Combining these achievements with the progress made with liquid flatjet technology has opened a new frontier of soft-X-ray spectroscopy of donor-acceptor systems in solution phase using the table-top water window HHG approach.
This activity will be pursued in close collaboration with Dr. Arnaud Rouzée (Project 2.1). An intense collaboration with in-house scientists involved in development of long-wavelength driver pulses (Project 1.2) will enable further improvement in photon flux and accessible spectral ranges towards the O K-edge and the 3d-metal L-edges, with which charge transport phenomena can be studied even more intensively. Third party funding comes from the Leibniz Gemeinschaft (SAW-2016-1, 2017-2020), an ERC Advanced Grant (XRayProton, Nibbering, 2018-2024), ITN Network Smart X, and the Leibniz Gemeinschaft (SAW-2023-1, 2024-2027).
1. Table-top approach to liquid phase X-ray absorption spectroscopy using HHG with long wavelength driver pulses and flatjet technology.
2. Extreme high-order harmonics spectra covering the water window C and N K-edge spectral regions.
3. X-ray absorption spectra measured for particular solutes in the water window, depicted as solid black lines. Dashed lines indicate the solvent water only response. Blue and orange thin lines are spectra measured at the BESSYII storage ring facility. These reference measurements have been convoluted with the spectral resolution of the HHG set-up spectrometer, for a direct comparison between the XAS HHG and BESSYII carbon and nitrogen K-edge results in the spectra shown in the right column.