Coverage-Dependent Anchoring of 4,4 '-Biphenyl Dicarboxylic Acid to CoO(111) Thin Films

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Details zur Publikation

Autor(en): Mohr S, Schmitt T, Döpper T, Xiang F, Schwarz M, Görling A, Schneider MA, Libuda J
Zeitschrift: Langmuir
Verlag: AMER CHEMICAL SOC
Jahr der Veröffentlichung: 2017
Band: 33
Heftnummer: 17
Seitenbereich: 4178-4188
ISSN: 0743-7463
eISSN: 1520-5827


Abstract

We investigated the adsorption behavior of 4,4'-biphenhyl dicarboxylic acid (BDA) on well-ordered CoO(111) films grown on Ir(100) as a function of coverage and temperature using time-resolved and temperature programmed infrared reflection absorption spectroscopy (TR-IRAS, TP-IRAS) in combination with density functional theory (DFT) and scanning tunneling microscopy (STM) under ultrahigh vacuum (UHV) conditions. To compare the binding behavior of BDA as a function of the oxide film thickness, three different CoO(111) film thicknesses were explored: films of about 20 bilayers (BLs) (approximately 5 nm), 2 BLs, and 1 BL. The two carboxylic acid groups of BDA offer two potential anchoring points to the oxide surface. At 150 K, intact BDA adsorbs on 20 BL thick oxide films in planar geometry with the phenyl rings aligned parallel to the surface. With decreasing oxide film thickness, we observe an increasing tendency for deprotonation and the formation of flat-lying BDA molecules anchored as dicarboxylates. After saturation of the first monolayer, intact BDA multilayers grow with molecules aligned parallel to the surface. The BDA multilayer desorbs at around 360 K. Completely different growth behavior is observed if BDA is deposited above the multilayer desorption temperature. Initially, doubly deprotonated dicarboxylates are formed by adopting a flat-lying,orientation. With increasing exposure, however, the adsorbate layer transforms into upright standing monocarboxylates. A sharp OH stretching band (3584 cm(-1)) and a blue-shifted CO stretching band (1759 cm(-1)) indicate weakly interacting apical carboxylic acid groups at the vacuum interface. The anchored monocarboxylate phase slowly desorbs in a temperature range of up to 470 K. At higher temperature, a flat-lying doubly deprotonated BDA is formed, which desorbs and decomposes in a temperature range of up to 600 K.


FAU-Autoren / FAU-Herausgeber

Döpper, Tibor
Lehrstuhl für Theoretische Chemie
Görling, Andreas Prof. Dr.
Lehrstuhl für Theoretische Chemie
Libuda, Jörg Prof. Dr.
Professur für Physikalische Chemie
Mohr, Susanne
Lehrstuhl für Physikalische Chemie II
Schmitt, Tobias
Lehrstuhl für Festkörperphysik
Schneider, M. Alexander Prof. Dr.
Professur für Experimentalphysik
Schwarz, Matthias
Lehrstuhl für Physikalische Chemie II
Xiang, Feifei
Lehrstuhl für Festkörperphysik


Zitierweisen

APA:
Mohr, S., Schmitt, T., Döpper, T., Xiang, F., Schwarz, M., Görling, A.,... Libuda, J. (2017). Coverage-Dependent Anchoring of 4,4 '-Biphenyl Dicarboxylic Acid to CoO(111) Thin Films. Langmuir, 33(17), 4178-4188. https://dx.doi.org/10.1021/acs.langmuir.7b00465

MLA:
Mohr, Susanne, et al. "Coverage-Dependent Anchoring of 4,4 '-Biphenyl Dicarboxylic Acid to CoO(111) Thin Films." Langmuir 33.17 (2017): 4178-4188.

BibTeX: 

Zuletzt aktualisiert 2018-22-08 um 16:23