Studies of Nanostructured Layers with UV-VIS Spectroscopic Ellipsometry

In this report a model analysis is presented for three different nanostructured layers: silicon nanotips (SiNTs), gold nanosandwiches and Split Ring Resonators (SRR). The last two materials are metamaterials and both may show a negative refraction index. Experimental data are obtained for every sample using a variable angle spectroscopic ellipsometer. For the gold nanosandwiches, also an infrared ellipsometric measurement is done. For complex layers like these, advanced modeling is necessary. A recently developed analysis program including options for both anisotropic permittivity and permeability is used. A realistic model is presented in this report for the gold nanosandwiches, which also includes the magnetic activity in the layer itself. The results for the nanosandwiches are reasonable, and a magnetic oscillation is found in the horizontal plane at around 260 nm although it was not expected to have a resonance that far in the UV-range. For the SiNTs and the SRR it was not possible to create an acceptable model

Cobalt containing nano-islands on Ge(111)-c(2 x 8)

The structural and electronic properties of Co containing islands on Ge(111)-c(2 × 8) surfaces have been studied using scanning tunneling microscopy and spectroscopy. Room temperature deposition of a sub-monolayer amount of Co and subsequent annealing at 500 K lead to the formation of (√13 × √13)R13.9° reconstructed islands, whereas annealing at 750 K results in (2 × 2) reconstructed islands. The latter type of islands has heights up to several atomic layers. We find that, in analogy with Co on Si(111), the (2 × 2) islands consist of CoGe2, condensed in a fluorite structure. Each Co(111) layer is encapsulated between two close packed Ge layers, while the outermost trilayer is terminated by an additional layer of Ge adatoms in a (2 × 2) registry. The (√13 × √13)R13.9° structure can be considered as a precursor to the CoGe2 crystallites with triangular trilayer patches, composed of three embedded Co atoms terminated by six Ge adatoms. The remaining dangling bond transfers charge to surrounding Ge atoms in the bilayer. The different domains in the (2 × 2) islands are separated by three types of boundaries. Two types of domain boundaries are dynamic, whereas the third type of domain boundary is static. The (2 × 2) domains show a faint (6 × 2) superstructure, which is tentatively attributed to the aligned Co defects at the interface. Scanning tunneling spectroscopy measurements indicate the presence of Co atoms in the (2 × 2) and (√13 × √13)R13.9° reconstructed islands

Dynamics of Au-induced nanowires on Ge(001)

We have studied the dynamics of Au-induced nanowires on Ge(001) using scanning tunnelling microscopy. The ridges of these nanowires consist of buckled dimers that have their dimer bond aligned in a direction perpendicular to the nanowire direction. Neighbouring dimers have a preference to buckle in an opposite direction, leading to rows with a zigzag appearance. Dimers located at anti-phase boundaries continuously flip back and forth between their two buckled configurations. This process is thermally induced and occurs at an average frequency of 25 Hz at room temperature.\ud \u

Structural and Electronic Properties of Au Induced Nanowires on Ge(001)

The structural and electronic properties of Au induced self-organized nanowires on Ge(001), prepared by different procedures, are investigated with scanning tunnelling microscopy and spectroscopy at room temperature and 77 K. We find that the Au induced nanostructures are identical for the different preparation procedures. The Au induced nanowires are comprised of dimers that have their bond aligned in a direction perpendicular to the nanowire. The dimers are buckled, leading to a 2× periodicity along the nanowires. Dimers located at antiphase boundaries are dynamic and flip back and forth between two buckled configurations. The troughs between the nanowires have a depth of several atomic layers. Finally, the differential conductivities of the nanowires and the troughs are very comparable in magnitude

Towards a Circular Bioeconomy. VOLATILE FATTY ACID PLATFORM FOR BIOWASTE RECYCLING

Resources in general are not infinitely available, and also renewable resources if consumed outside their normal replacement cycles become scarce. Therefore, the establishment of a circular bioeconomy must respect natural systems and replacement cycles of organic carbon thereby reducing environmental pressure of human consumption. Upcycling of side and biowaste streams towards added value compounds represents hereby a critical aspect reducing land system change and fertilizer use for biomass supply for the bioeconomy. The development of a Volatile Fatty Acids Platform (VFAP) represents an important cornerstone for the upcycling of heterogenous municipal biowaste streams.This e-book was prepared in the context of the EU funded project VOLATILE in accordance with the grant agreement No 720777 (European Union’s Horizon 2020 research and innovation programme)