Regensburg 2022 – scientific programme

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O: Fachverband Oberflächenphysik

O 82: Electronic Structure of Surfaces 2

O 82.1: Talk

Friday, September 9, 2022, 10:30–10:45, S053

Electron- and Hole-Like Transport in Shockley Type Surface States Detected by MONA — Andreas Christ, •Markus Leisegang, Patrick Härtl, and Matthias Bode — Physikalisches Institut, Experimentelle Physik II, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany

In recent years, we have established the STM-based molecular nanoprobe (MONA) technique to detect the transport of hot charge carriers over distances of a few nanometers [1,2]. In short, MONA uses a charge carrier-driven molecular switching events, such as a tautomerization or rotation, to detect currents injected a few nanometers away. Earlier experiments performed on Ag(111) showed that the surface state characteristic for fcc(111) surfaces facilitates effective charge transport between the charge injection point at the tip position and a single phthalocyanine (HPc) detector molecule [3]. Since, however, the energy threshold for tautomerization of HPc exceeds the energy onset of the Ag(111) surface state (E=−63 meV), hole transport remained inaccessible. In order to investigate the influence of the band structure on the propagation of hot charge carriers we compare results of MONA experiments performed on Ag(111) with the isoelectronic Cu(111) surface. Our results reveal that due to the lower surface state onset in Cu(111) at E = −440 meV hole-like charge transport can also be detected.
[1] M. Leisegang et al., Nano Lett. 18, 2165-2171 (2018)
[2] M. Leisegang et al., Phys. Rev. Lett. 126, 146601 (2021)
[3] J. Kügel et al., Nano Lett. 17, 5106 (2017)