Regensburg 2019 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 69: Poster Wednesday: Organic Molecules on Inorganic Surfaces
O 69.4: Poster
Mittwoch, 3. April 2019, 17:45–20:00, Poster B2
Spectroscopic studies of thin hemin and cytochrome-c films using a PEEM with fs-laser and He-I excitations — •Franz Niklas Knoop1, Jonas Darius Fortmann1, Ansgar Pausch1, Klaus Stallberg2, Gerhard Lilienkamp1, Uwe Schröder3, and Winfried Daum1 — 1IEPT, TU Clausthal — 2Surface Physics, Uni Marburg — 3IÖNC, TU Braunschweig
Microbial fuel cells (MFC) offer the potential to convert chemical energy of organics in waste water to electricity. Besides questions of technical realization, the electron transfer process in the bacterial biofilms is topic of current research. Previous studies suggest that redox-active, membrane-associated cytochromes play a crucial role in the transfer processes for Geobacter sulfurreducens, a promising candidate for MFCs. Aiming at a spectromicroscopic characterization of bacteria films, we studied thin films of the protein cytochrome c and the porphyrin hemin b, the latter being similar to the redox-active center heme c of the protein, using photoelectron emission microscopy (PEEM) with fs-laser excitation. For cytochrome c and hemin b we observe in our laser excitation spectra a pronounced Soret band at 415 nm and 400 nm, respectively, with very strong spectral broadening in the case of condensed hemin. While for cytochrome c laser-induced changes of the Soret band spectra were observed, hemin b spectra are not affected by laser irradiation. As a second route, we evaluate the possibilities of PEEM with excitation from a He-I UV light source and present first spectroscopic results for these films. We acknowledge financial support of the research group ElektroBak by the State of Lower Saxony.