Time: Nov. 25th, 2015 09:30 A. M.
Location: Conference Room of Basic Energy Science Building
Lecturer：Prof. Christof W？ll
Karlsruhe Institute of Technology, Germany
Abstract:
In the past decades, Infrared Reflection Absorption Spectroscopy (IRRAS) has emerged as a very powerful tool for characterizing molecular adsorbates on metal surfaces. Until recently, however, the low reflectivity in the infrared regime of metal oxides rendered this important spectroscopic technique practically useless for this important class of materials. As a result, the application of the so-called Surface-Science approach to understand heterogeneous catalysis on oxides could not be applied directly. The situation changed as a result of progress in instrumentation achieved over the last years and today IRRAS-data for adsorbates on dielectric substrates can be measured in an almost routine fashion.
In this talk we will present the first IRRAS data for two important oxides, ZnO and CeO2. For the case of ZnO we will demonstrate for two adsorbates, CO and CO2, that IRRAS studies on oxide samples allow for a direct experimental determination of the adsorbate geometry, when considering all three components of the incident polarized light separately as well as performing azimuth dependent measurements. As regards IRRAS on dielectric substrates, it is crucial to consider that the so-called “surface selection rule” governing IRRAS on oxides does not apply. As a result, the interpretation of IRRAS-data is more complicated, yet allows extracting much more information by using s- and p-polarized light as well as different incident directions (see Fig. 1). We will illustrate the potential of this method using the example of carbon dioxide adsorbed on ZnO(10-10), where we find an upright standing tridentate carbonate species oriented along the (0001)-direction. In the case of CeO2(111) single crystals, we will show that also on this surface CO can be used as a probe molecule to determine vacancy concentrations on ceria surfaces. Finally, we will show for TiO2 and ZnO that IRRAS can also be used to study electrons in polaronic trap states, an important intermediate in photochemistry.
Introduction:
Academic Education
Physics (1979 - 1984) University of G？ttingen, Diploma graduation
Scientific Education
Habilitation: Faculty for Physics, University of Heidelberg, 1992
Promotion: Physics, University of G？ttingen, MPI Str？mungsforschung
PhD graduation: Physics, University of G？ttingen, MPI Str？mungsforschung, 1987 (with J.P. Toennies)
Career
2009–Present, Director, Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT),Campus North
1997–2009, Full Professor (C4), Lehrstuhl für Physikalische Chemie I, Ruhr-University Bochum
1993–1996, Heisenberg Fellow of the Deutsche Forschungsgemeinschaft, Research Activities at the Institut für Physikalische Chemie, University of Heidelberg and MPI für Str？mungsforschung University of G？ttingen
1989–1992, Research Assistant at Institut für Physikalische Chemie, University of Heidelberg(Prof. M. Grunze)
1988–1989, Postdoc at IBM Research Laboratory, San Jose, California, USA
1984–1987, Scientific Staff, MPI Str？mungsforschung, University of G？ttingen
Other (Selected other professional activities)
Since June 2013–Present, Member of German Academy of Sciences Leopoldina
2011–Present, Speaker of the program BioInterfaces, funded by the German Helmholtz-Association
2010, Scientific Program organizer (together with A. G？lzh？user, Bielefeld) of the Annual German Physical Chemistry Society (Bunsengesellschaft) Meeting
2006–2009, Coordinator of the EU-strep-Program SURMOF, “Anchoring of metal-organic frameworks, MOFs, to surfaces”
2001–2007, Speaker of the DFG-Schwerpunkt-Program 1121 “Organische Feldeffekttransistoren”
2000–2009, Speaker, DFG Priority Program 558 "Metall-Substrat-Wechselwirkungen in der Heterogenen Katalyse"
Since 2000, Member of the Editorial Boards of “Progress in Surface Science”
Since 1998, Member of the Editorial Boards of “Surface Review and Letters”
Honors
2006 - 2007 Visiting Professor at Nagoya University, Japan, Prof. K. Seki
2001 Visiting Professor at the University of Illinois at Urbana/Champaign, Materials Research Laboratory,Prof. Dr. R. Nuzzo
1988 Otto-Hahn Medal of the Max-Planck-Gesellschaft for PhD-Thesis
Publications
> 400 peer-reviewed publications in international journals including review articles, peer-reviewed conference proceedings and book-chapters; ca. 10000 citations without self-citations.
Contacts: FANG Kun (Group 505)