Methods and Instruments

Due to the wide range of our activities from synthesis of nanostructured catalysts (such as, e.g., colloidal nanoparticles, aerogels, or nanoporous metals) via catalyst tests in many different gas phase reactions (including Fischer-Tropsch) to model studies on surface chemistry either experimentally in ultrahigh vacuum or by calculations, we do employ an equivalently wide range of instruments and techniques. The following list provides an overview of major tools available in our laboratories – and at theorist Lyudmila Moskaleva’s fingertip in her office:

Catalyst tests and characterization

• Fourier-Transform Infrared Spectroscopy (FTIR) (Bruker Vertex 80 v and Varian with modified DRIFTS cell for in situ studies)
• Gas Chromatography (GC)
• UV-vis Spectroscopy
• Infrared Gas Analysis (IRAS)
• Atom Absorption Spectroscopy and Surface area determination by the BET method

Thanks to support by other groups on-campus and cooperation with the Fraunhofer Institute for Manufacturing Technology and Advanced Materials we also have access to X-ray Diffraction, Raman Spectroscopy, and Thermogravimetric Analysis (TGA) as well as Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), both including elemental analysis by Energy-Dispersive X-ray Spectroscopy or Energy Loss Spectroscopy.

Model studies in ultrahigh vacuum (UHV)

We operate two Multiprobe UHV systems made by Omicron Nanotechnology, partly modified, comprising:

• X-ray photoelectron spectroscopy (XPS)
• Temperature-programmed desorption or reaction spectroscopy (TPD/TPR)
• Scanning Tunneling Microscopy (STM)
• FTIR Spectroscopy (in reflection)
• Low-Energy Electron Diffraction (LEED) and Auger Electron Spectroscopy (AES)
• Systems for gas dosing, sources for Physical Vapor Deposition of metals or oxides
• Plasma Source for surface preparation (homebuilt)
• Reactor for Chemical Vapor Deposition (homebuilt) for thermal CVD, CVD via pulsed spray evaporation of the precursor, or Atomic Layer Deposition

Theory

Electronic structure calculations in the framework of density functional theory (DFT) are performed using periodic slab models.

Software:

• VASP with pseudo-potential based plane-wave (PW) and projector-augmented wave (PAW) methods

Instrumental developments

In order to extend the possibilities of sample manipulation and treatment for our model studies in UHV to better reflect the variety of nanostructured materials used as real catalysts, we have engaged in the development of novel tools:

• UHV-compatible Plasma Source
  A compact chamber for plasma treatment of sample surfaces was designed and built to be directly attached to our UHV systems in order to provide contamination-free transfer of samples between plasma treatment and surface analysis.

Current project:

Design of a compact UHV-compatible setup for pulsed spray evaporation-CVD of metals

Selection of Publications:

¹ B. Gehl, U. Leist, V. Aleksandrovic, P. Nickut, V. Zielasek, H. Weller, K. Al-Shamery, M. Bäumer, Design of a UHV-compatible RF plasma source and its application to self-assembled layers of CoPt₃ nanoparticles, Review of Scientific Instruments 77 (2006) 083902. DOI: 10.1063/1.2336192

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