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Structural Evolution of α-Fe2O3(0001) Surfaces Under Reduction Conditions Monitored by Infrared Spectroscopy

Schöttner, Ludger; Nefedov, Alexei; Yang, Chengwu; Heissler, Stefan; Wang, Yuemin; Wöll, Christof

Abstract (englisch):
The precise determination of the surface structure of iron oxides (hematite andmagnetite) is a vital prerequisite to understand their unique chemical and physical properties under different conditions. Here, the atomic structure evolution of the hematite (0001) surface under reducing conditions was tracked by polarization-resolved infrared reflection absorption spectroscopy (IRRAS) using carbon monoxide (CO) as a probe molecule. The frequency and intensity of the CO stretch vibration is extremely sensitive to the Valence state and electronic environments of surface iron cations. Our comprehensive IRRAS results provide direct evidence that the monocrystalline, stoichiometric a-Fe2O3(0001) surface is single Fe-terminated. The initial reduction induced by annealing at elevated temperatures produces surface oxygen vacancies, where the excess electrons are localized at adjacent subsurface iron ions (5-fold coordinated). A massive surface restructuring occurs upon further reduction by exposing to atomic hydrogen followed by Ar+-sputtering and annealing under oxygen poor conditions. The restructured surface is identified as a Fe3O4(111)/Fe1−xO(111)-biphase exposing both, Fe3+ and Fe2+ surface species. ... mehr

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Verlagsausgabe §
DOI: 10.5445/IR/1000096437
Veröffentlicht am 11.07.2019
DOI: 10.3389/fchem.2019.00451
Zitationen: 7
Web of Science
Zitationen: 7
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Funktionelle Grenzflächen (IFG)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2019
Sprache Englisch
Identifikator ISSN: 2296-2646
KITopen-ID: 1000096437
HGF-Programm 43.22.02 (POF III, LK 01)
Erschienen in Frontiers in Chemistry
Band 7
Seiten Art.Nr. 451
Bemerkung zur Veröffentlichung Gefördert durch den KIT-Publikationsfonds
Vorab online veröffentlicht am 25.06.2019
Schlagwörter iron oxide, CO adsorbed infrared spectroscopy, IR spectroscopy, reduced oxides, XPS
Nachgewiesen in Web of Science
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