Regensburg 2022 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 55: Poster Wednesday: Organic Molecules at Surfaces 2
O 55.16: Poster
Mittwoch, 7. September 2022, 18:00–20:00, P4
Chirality-induced electron spin filtering in chiral helicene mono-, double- and multilayers — •Ruwen Quenter1, Paul Valerian Möllers1, Karl-Heinz Ernst2, and Helmut Zacharias1 — 1Center for Soft Nanoscience, WWU Münster, Germany — 2Empa, Dübendorf, Switzerland
The transmission yield of electrons through molecules with chiral structure can depend on the electron spin. This phenomenon is established as chirality-induced spin selectivity (CISS).1 While initial demonstrations of CISS were conducted with, e.g., short DNA strands,2 studies with simpler molecules such as helicene potentially allow for a better insight into the mechanism. Previous work3 on CISS in ordered monolayers of heptahelicene ([7]H) demonstrated that while the preferentially transmitted spin orientation depends on the helicity of the molecules, no major influence of the substrate is evident. Since the CISS increases with the number of helical turns, we investigate how it evolves for double and multilayers of [7]H adsorbed on a Cu(332) surface. Photoelectrons were excited from the substrate by deep-UV laser pulses and transmitted through [7]H mono-, double or multilayers. Subsequently, the average spin polarization of the photoelectrons was measured via Mott scattering. With a [7]H monolayer a spin polarization of P≈8% was shown earlier3 and reproduced now. For the double and multilayers no increased spin polarization magnitude was found. 1 D. H. Waldeck et al., APL Mater. 9, 040902 (2021) 2 B. Göhler et al., Science 331, 894 (2011) 3 M. Kettner et al., J. Phys. Chem. Lett. 9, 2025 (2018)