Low-Energy Scale Excitations in the Spectral Function of Organic Monolayer Systems

Using high-resolution photoemission spectroscopy we demonstrate that the electronic structure of several organic monolayer systems, in particular 1,4,5,8-naphthalene tetracarboxylic dianhydride and Copper-phtalocyanine on Ag(111), is characterized by a peculiar excitation feature right at the Fermi level. This feature displays a strong temperature dependence and is immediatly connected to the binding energy of the molecular states, determined by the coupling between the molecule and the substrate. At low temperatures, the line-width of this feature, appearing on top of the partly occupied lowest unoccupied molecular orbital of the free molecule, amounts to only $\approx 25$ meV, representing an unusually small energy scale for electronic excitations in these systems. We discuss possible origins, related e.g. to many-body excitations in the organic-metal adsorbate system, in particular a generalized Kondo scenario based on the single impurity Anderson model.Comment: 6 pages, 3 figures, accepted as PRB Rapid Communication

Detection of Overhead Contact Lines with a 2D-Digital-Beamforming Radar System for Automatic Guidance of Trolley Trucks

The benefit of trolley truck systems is the substitution of the diesel fuel by the cheaper and more ecological electrical energy. Trolley trucks are powered by electricity fromtwo overhead contact lines, where one is the supply and the other the return conductor. Such trolley trucks are used for haulage at open pit mining sites but could also be used for freight traffic at roadways in the future. Automatic guidance prevents the trolley-powered trucks fromleaving the track and thus allows higher operating speeds, higher loading capacity, and greater efficiency. Radar is the ideal sensing technique for automatic guidance in such environments.The presented radar systemwith two-dimensional digital beamforming capability offers a compact measurement solution as it can be installed on top of the truck. Besides the distance measurement, this radar system allows to detect the location and inclination of the overhead contact lines by digital beamforming in two dimensions. Besides automatic guidance, the knowledge of the inclination of the overhead contact lines could allow automatic speed adaption, which would help to achieve maximum speed especially in hilly terrain

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Improved Performance of Flip Chip assembled MMIC Amplifiers on LTCC using a Photonic Bandgap Structure

Further cost reduction in today’s microwave frontends is strongly related to assembly technology as well as module technology. Depending on the particular mix of technologies, specific problems and chances can be addressed. In case of flip-chip on LTCC, various effects of performance degradation of the MMICs can be observed, some of which can be related to unwanted internal coupling of the microstrip IC due to the floating groundplane. For some MMICs a periodic structure below the chip can help to improve the characteristics of the assembled chip due to its ability to suppress a particular class of unwanted modes between the chip groundplane and the module ground. The periodic structure is proposed and measured results are given and discussed