Within the framework of the ICICP the collaborative research unit FOR1878 "Functional Molecular Structures on Complex Oxide Surfaces (FunCOS)"
has been established funded by the DFG. Click on the logo to the left to find detailed information.
Major research topics of the collaborating groups
Excited electronic states play an important role in many technological processes such as photochemistry, photovoltaics or semiconductor devices. The Fauster group uses angle-resolved photoelectron spectroscopy to study the lifetimes of electronic surface states excited by femtosecond lasers. With pump-probe techniques the various elastic and inelastic scattering processes can be studied in considerable detail. Systems studied range from image-potential states on metal surfaces to dangling bond states at semiconductor surfaces. In order to identify the influence of defects (e.g. adsorbates or steps) on the various scattering processes, the sample surfaces have to be well characterized. For this the expertise at the chair in LEED and STM is used.
The research focuses on the local electronic structure of surfaces and of adsorbates or nanostructures on surfaces (molecules, atoms). Of particular interest are thin oxide films, alloy surfaces and graphene. The main research instrument is the (low-temperature) Scanning Tunneling Microscope but also LEED is employed for structural characterization.
The diamond research group at Erlangen has focussed on the special semiconductor properties of diamond that
qualifies this extreme wide band gap semiconductor for electronic applications.
Besides research on classical interface-controlled devices like semiconductor
hetero-junctions for light detection and emisssion, the group has performed
pioneering work on the p-type surface transfer doping of diamond, an
effect occuring at liquid and gaseous interfaces of hydrogen-terminated
intrinsic diamond. This effect is also in the center of the groups contribution
to the recently established EU research and training network
(Diamond Research on Interfaces for Versatile Electronics) between
twelve active research groups from eight Eruropean countries.
P. Strobel, M. Riedel, J. Ristein and L. Ley, "Surface transfer doping of diamond, NATURE 430, 439 (2004)
F. Maier, M. Riedel, B. Mantel, J. Ristein , and L.Ley, "The origin of surface conductivity in diamond ", Phys. Rev. Lett. <85, 3472 (2000)
Chemical reactivity as well as magnetic and optical properties of steps and other one-dimensional structures on surfaces are determined by electronic structure calculations on the basis of density functional theory. The latestdevelopments of this theory also allow considering the time-dependent phenomena and excitation spectra. Within this collaboration we are workingon the electronic and magnetic properties of vicinal surfaces of Pd and one-dimensional superstructures on these surfaces, and on the excitationspectra and electron correlations on flat and structured surfaces.
The research activities of the Steinrück group focus on the area of surface and interface science with the main research interests in:
- New materials with novel electronic, geometric and chemical properties (metals, alloys, oxides, semiconductors, organic layers, ionic liquids; ultrathin layers and lateral nanostructures; growth modification and electronic, geometric and chemical properties)
- Elementary steps of surface reactions (various model reactions on structured surfaces with particular emphasis on the influence of the surface structure on reactivity and reaction pathways; fundamental physical and chemical understanding of the mechanisms and processes involved).
- Development and construction of scientific apparatus (photoelectron spectrometer for in-situ XPS at synchrotron radiation sources; "high-pressure XPS" setup for measurements up to 1 mbar).
The applied experimental methods include electron spectroscopy (XPS, UPS, AES, NEXAFS), scanning electron, scanning Auger and scanning tunneling microscopy (SEM, SAM, STM), electron diffraction (LEED), low energy ion scattering (LEIS), temperature programmed desorption (TPD) and molecular beam methods.
The expertise of the workgroup is centred around the kinetics and dynamics of chemical reactions on complex surfaces, with a special focus on applications in heterogeneous catalysis, environmental catalysis and energy technology. Towards this aim, nanostructured model surfaces are developed and investigated. The dynamics and kinetics of chemical reactions on their surfaces is probed using multi-molecular beam methods, reactor methods and time-resolved spectroscopies under reaction conditions. Mechanistic and kinetic studies are performed from ultrahigh vacuum conditions up to atmospheric pressure and complemented by microkinetic modelling. The aim of this work is to contribute to a microscopically well-founded mechanistic and kinetic understanding of catalytic reactions on complex surfaces under realistic conditions, thus helping to overcome the gaps between fundamental surface science and applied research.
"Chemical Bistability on Catalyst Nanoparticles", V. Johanek, M. Laurin, A. W. Grant, B. Kasemo, C. R. Henry, J. Libuda*, Science 304, 1639 (2004).
"Molecular Beam Experiments on Model Catalysts: Activity and Selectivity of Specific Reactive Sites on Supported Nanoparticles", J. Libuda*, ChemPhysChem 5, 625 (2004).
"Molecular Beam Experiments on Model Catalysts", J. Libuda*, H.-J. Freund, Surface Science Reports 57, 157 (2005).
"Size-Dependent Oxidation Mechanism of Supported Pd Nanoparticles", T. Schalow, B. Brandt, D. E. Starr, M. Laurin, Sh. K. Shaikhutdivov, S. Schauermann, J. Libuda*, H.-J. Freund, Angew. Chem. Int. Ed. 45, 3693 (2006).
"Adsorption and Reaction of Methanol on Palladium Model Catalysts: Microscopic-Level Studies from Ultrahigh Vacuum to Ambient Pressure Conditions",
M. Bäumer, H.-J. Freund, J. Libuda, K. M. Neyman, N. Rösch, G. Rupprechter, PCCP 9, 3541-3558 (2007).
The emphasis of the research is lying on the preparation and investigation of ultrathin organic films on metal single crystals and structured templates. The interaction between the adsorbed molecules and the substrate induces structural phases in the organic adlayer (e.g., different molecular orientation, different gemoetric structures), which may differ from the bulk phases. In combination with template structures, organic nanostructures are formed for vacuum-deposited films or for molecule deposition from solutions. Spatially resolved x-ray techniques with lateral resolution below 30 nm allow full spectroscopic insight into nanostructures using the x-ray absorption contrast.
Teaching and research at LKO
cover aspects of surface science and technology of materials, including
electrochemistry, surface analysis, corrosion as well as micro- and
nanostructuring. A wide range of characterization and modification
techniques is used to study the functionalization and degradation
of metal- and semiconductor surfaces and interfaces. Research projects
at LKO are of a highly transdisciplinary nature and target fundamental
as well as applied aspects.
Examples of current research topics are:
- Self-organized nanopatterning such as the formation of self organized nanotubes/nanopores by anodization (materials: InP, GaP, TiO2, ZrO2, W, Ta, Nb, Hf)
- Self-organized monolayers as e-beam resist
- E-beam induced nano-masking for metal electrodeposition on semiconductor surfaces
- AFM induced nanopatterning of semiconductor surfaces
- Decoration of surface reconstruction sites
- Selective Surface Activation using FIB implantation
- Tip-induced nanostructuring of AuxCuy-alloys with an electrochemical STM