Berlin 2015 – scientific programme

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O: Fachverband Oberflächenphysik

O 12: Inorganic/Organic Interfaces: Growth II

O 12.4: Talk

Monday, March 16, 2015, 15:45–16:00, MA 005

Vibrational properties of stacked and intermixed (CuPc + PTCDA) layers on Ag(111) — •Sebastian Thussing and Peter Jakob — Fachbereich Physik, Philipps-Universität Marburg, Renthof 5, 35032 Marburg, Germany

The vibrational properties and thermal evolution of stacked and intermixed CuPc and PTCDA layers deposited on Ag(111) have been investigated using IR absorption spectroscopy, SPA-LEED, and TDS. For the mixed layers four different monolayer phases have been found depending on the CuPc:PTCDA ratio. Ordering of cold deposited layers sets in after annealing to 250 K and prevails up to 500 K. All mixed phases display characteristic spectroscopic signatures in vibrational spectra. The monolayer phases of CuPc and PTCDA show pronounced interfacial dynamical charge transfer (IDCT). Interestingly, IDCT is attenuated for mixed layers, especially for the respective minority species. This is attributed to energetic shifts of the partially filled 'former LUMO' as a result of intermolecular coupling (through metal charge transfer). For stacked (bi)layers thermal annealing leads to interlayer exchange for CuPc on PTCDA as well as for PTCDA on CuPc which we attribute to the extra energy gain provided by intermixing and charge transfer between the constituents within the monolayer. For PTCDA on CuPc intermixing is found already for T > 200K, while the reverse stacking is stable up to 450K.