Regensburg 2025 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 50: Poster Organic Molecules on Inorganic Substrates: Adsorption and Growth

O 50.6: Poster

Dienstag, 18. März 2025, 18:00–20:00, P2

Structural and vibrational properties of mixed (CuPc + P4O) molecular layers on Ag(111) — •Yeondu Kim, Ravi Priya, and Peter Jakob — Department of Physics, Philipps University Marburg, Germany

Structural properties of mixed layers comprising CuPc and P4O on Ag(111) and their thermal evolution have been investigated by means of Fourier-transform infrared absorption (FT-IRAS) and electron diffraction (SPA-LEED). For this material combination several long-range ordered phases at different relative ratios are found. Their formation and thermal stability have been analyzed in the temperature range 80 - 500 K, limited by thermal desorption and/or dissociation of the CuPc and P4O compounds at high temperature. Lateral interactions between CuPc and P4O within the mixed layers lead to characteristic frequency shifts of out-of-plane modes. In parallel, the intensities of in-plane vibrational modes of CuPc and P4O are strongly attenuated when adsorbed at nearby locations, indicating a major change in the associated interfacial dynamical charge transfer (IDCT). Specifically, IDCT that is quite prominent for the pure CuPc/Ag(111) and P4O/Ag(111) monolayers, is substantially attenuated for the mixed layers. This is ascribed to a through-metal charge transfer from CuPc to P4O that is associated with an upshift of the CuPc former LUMO and the correlated downshift of the P4O former LUMO. These correlated shifts lead to substantially lower density of states at the fermi level for both molecular species and thereby a weakening of IDCT induced bands.

Keywords: CuPc; Pentacenetetrone; IRAS; SPA-LEED; IDCT