Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 54: Focus Session: Molecular Nanostructures on surfaces - New Concepts towards Complex Architectures III

O 54.9: Vortrag

Mittwoch, 14. März 2018, 12:45–13:00, MA 004

Infrared Reflection Absorption Spectroscopy Study of Phenylphosphonic Acid on Co3O4(111), CoO(111), and CoO(100) — •Matthias Schwarz, Christian Schuschke, Chantal Hohner, Thais Nascimento Silva, and Jörg Libuda — Lehrstuhl für Physikalische Chemie II, Universität Erlangen-Nürnberg

We applied infrared reflection adsorption spectroscopy (IRAS) in a surface science model study under ultra-high vacuum (UHV) conditions to investigate the coverage dependent growth and thermal stability phenylphosphonic acid (d1,d2-PPA) multilayer and monolayer films on well-ordered Co3O4(111), CoO(111) and CoO(100) films on Ir(100). At 180 K, identical amorphous multilayers of intact d1,d2-PPA form on all three surfaces. They rearrange at 250 K, leading to similar recrystallized phases for all three surfaces, however with different molecular orientations. Above 340 K the multilayers desorb and only the chemically anchored monolayers remain on the surface. These are stable up to at least 550 K for all surfaces. However, surface binding and coverage dependencies in the monolayer are highly structure dependent. For d1,d2-PPA on Co3O4(111), a tridentate binding mode and full deprotonation was found for low coverages. At higher coverage, this species is replaced by partly protonated bidentate. In contrast, fully deprotonated tridentate dominates for all coverages on CoO(100). On the oxygen terminated CoO(111) bidentate species are found in the zero coverage limit. With increasing coverage, the surface restructures such that tridentate binding mode is enabled. Close to saturation, bidentate binding dominates again, presumably enabling more dense packing.