SKM 2023 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 28: Organic Molecules on Inorganic Substrates III: Adsorption and Growth I

O 28.2: Vortrag

Dienstag, 28. März 2023, 10:45–11:00, CHE 89

Homo- and Heterochiral Phases of Quinacridone Monolayers on Ag(110) and Ag(111) — •Ravi Priya, Weishan Wu, Keda Jin, and Peter Jakob — Fachbereich Physik, Philipps-Universität Marburg, Germany

When adsorbed on a surface, parallel-oriented quinacridone (QA) transforms into a chiral species and lateral interaction between neighboring molecules will depend on the types of enantiomers facing each other. On Ag(111) a homochiral phase comprising rows of (identical) QA has been reported that, upon thermal annealing, converts to a heterochiral phase consisting of alternating pairs (dimers) of the two enantiomers [1]. In our study, we have refined the structural analysis of QA/Ag(111) phases and have extended the available database to QA on Ag(110). Besides SPA-LEED, IR-spectroscopy and TDS were employed to characterize the various phases and associated phase transformations in detail. From IRAS and TDS a stronger molecule-substrate interaction is deduced for Ag(110) as compared to Ag(111). In parallel, interfacial dynamical charge transfer (IDCT) is considerably enhanced for QA/Ag(110) which is ascribed to an extra downshift of the QA-LUMO, increasing its DOS at the fermi energy. Interestingly, IDCT vanishes completely upon the transition of the homochiral to the heterochiral arrangement, both on Ag(111) and Ag(110). This could be explained by a completely empty, or a fully occupied LUMO [2]. As this transition is accompanied by a notable increase in the work function, we conclude that the latter applies.

[1] https://doi.org/10.1021/jp502148x

[2] https://doi.org/10.1103/PhysRevLett.126.116801