Materials for Renewable Energy  
Hydrogen and Hydrides
Structure and Dynamics
Stability and Kinetics
Theoretical Modelling

Spectroscopy on Metal Hydrides
The knowledge of the properties of the complex hydrides and the understanding of the hydrogen sorption mechanism will greatly improve the scientific basis of hydrogen storage in complex hydrides and will help to develop the hydrogen storage material of the future. Optical Spectroscopy is a versatile tool to measure these properties.
Optical spectroscopy is an established method in solid state physics. It is compatible to the experimental conditions needed in hydrogen storage, e.g. high pressures and temperatures. The Laboratory OHym makes use of this to measure, characterize and identify hydrogen storage materials. We will focus on the investigation of the physical properties of p-element complex hydrides. Optical spectroscopy in the low energy range (infrared spectroscopy) and Raman spectroscopy can detect parts of the vibration spectra due to optical selections rules. Transitions originating from hydrogen vibrations have high energy and are easily detectable by IR and Raman. Thus, we will use IR and Raman as a characterization method to support materials development. In contrast to diffraction methods (e.g. X-ray diffraction), also liquids can be investigated, as Raman and IR spectroscopy probe the local structure of matter. Optical spectroscopy will give insight into the crystalline and electronic structure of complex hydrides. Typical measurement times are in the order of minutes and can be reduced down to seconds. Fast sorption kinetics, which is connected to structural and dynamical changes in the minutes to seconds' time regime, can thus be perfectly studied with optical spectroscopy. Hydrogen-Deuterium isotope exchange experiments are planned to separate mass transport effects of the various constituents involved. With this we hope to find answers to the question, which process is rate-determining (dissociation, diffusion etc.) in hydrogen sorption. The experimental results will be compared with theoretical ab-initio calculations of the vibration spectra and thermodynamics of the proposed/detected intermediates.

Dr. Andreas Borgschulte

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