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Hexa-perihexabenzocarbonate (HBC) are small cluster of a graphene plane with various side groups for stabilization. Due to theire ate geometry they are ideal candidates to study surface enhanced Raman spectroscopy (SERS). Very thin films HBC were vaopur deposited to different SERS-active Ag-surfaces. The enhancement of the Raman signal was studied with the goal to develop an Ag-surface of optimum enhancement, for multiple use and very simple sample preparation. For the current surface the observed enhancement is up to 10 6 . For SWNT filled with Ag-particles the SERS effect could also be shown - but enhancement was only a factor 10.

A central parameter to describe the formation of porosity and macrosegregation during casting processes is the permeability of the dendritic mushy zone. To determine this specific feature for a binary Al-18wt.%Cu alloy, flow simulations based on the Lattice Boltz-mann (LB) method were performed. The LB method allows an efficient solving of fluid flow problems dealing with complex shapes within an acceptable period of time. The 3D structure required as input for the simulations was captured with X-ray microtomography, which enables the generation of representative geometries for permeability investigations. Removing the eutectic phase from the measured dataset generated a remaining network of solid primary dendrites. In the simulations, a pressure gradient was applied to force the liquid through the free interdendritic channels. The permeability of the structure was then calculated from the resulting flow velocity pattern using Darcy's law. To examine the influence of different boundary conditions on the results obtained, several simulations were conducted.