Dresden 2020 – scientific programme
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O: Fachverband Oberflächenphysik
O 49: Poster Session - Organic Molecules on Inorganic Substrates: Electronic, Optical and Other
O 49.7: Poster
Tuesday, March 17, 2020, 18:15–20:00, P2/EG
Application of multi-photon PEEM to a biological system: Geobacter sulfurreducens — •Franz Niklas Knoop1, Hilke Sophie Wichmann2, Gerhard Lilienkamp1, and Winfried Daum1 — 1IEPT TU Clausthal — 2IÖNC TU Braunschweig
Excitation of the molecular Soret transition of porphyrins by short tunable laser pulses has made possible multi-photon photoelectron emission microscopy (nP-PEEM) studies of porphyrin thin films and nanoplasmonic porphyrin hybrid systems with high molecular sensitivity [1]. More recently, we have also applied this method to films of the protein cytochrome c whose chromophoric group is a porphyrin. In this contribution we report on nP-PEEM results for a biological system, Geobacter sulfurreducens which is a promising candidate for microbial fuel cells. This bacterium as well as its extracellular matrix is rich of cytochrome c which is probed in our PEEM experiments using appropriates laser wavelengths. While films of porphyrin molecules such as MgTPP are very stable against irradiation with 100 fs laser pulses, photoemission from cytochrome c films as well as from Geobacter sulfurreducens shows substantial intensity and spectral changes upon laser irradiation. Our experiments point to thermal effects because moderate heating of the sample also increases the photoemission intensity from Geobacter sulfurreducens. We present and discuss Soret-resonant single-wavelength and laser-spectroscopic PEEM results obtained from single bacteria and bacteria films.
[1] K. Stallberg, G. Lilienkamp, W. Daum, J. Phys. Chem. C 121, 13833 (2017)