Electronic excitation spectrum of doped organic thin films investigated using electron energy-loss spectroscopy

The electronic excitation spectra of undoped, and potassium as well as calcium doped phenantrene-type hydrocarbons have been investigated using electron energy-loss spectroscopy (EELS) in transmission. In the undoped materials, the lowest energy excitations are excitons with a relatively high binding energy. These excitons also are rather localized as revealed by their vanishing dispersion. Upon doping, new low energy excitation features appear in the former gaps of the materials under investigation. In K$_3$picene and K$_3$chrysene they are characterized by a negative dispersion while in Ca$_3$picene they are dispersionless

Subordination of Shareholder Loans from a Legal and Economic Perspective

Gesellschafterdarlehen, Volkswirtschaft, Recht, Bewertung, Shareholder loan, Economy, Law, Evaluation

Absence of photoemission from the Fermi level in potassium intercalated picene and coronene films: structure, polaron or correlation physics?

The electronic structure of potassium intercalated picene and coronene films has been studied using photoemission spectroscopy. Picene has additionally been intercalated using sodium. Upon alkali metal addition core level as well as valence band photoemission data signal a filling of previously unoccupied states of the two molecular materials due to charge transfer from potassium. In contrast to the observation of superconductivity in K_xpicene and K_xcoronene (x ~ 3), none of the films studied shows emission from the Fermi level, i.e. we find no indication for a metallic ground state. Several reasons for this observation are discussed.Comment: 15 pages, 6 figure

W42 - a scalable spatial database system for holding Digital Elevation Models

The design of a scalable system for holding spatial data in general and digital elevation models (DEMs) in specific has to account for the characteristics of data from various application fields. The data can be heterogeneous in coverage, as well as in resolution, information content and quality. A database aiming at the representation of world-wide DEMs has to consider these differences in the design of the system with respect to the structure and the algorithms. The database system W42, which is presented in the work at hand, is a scalable spatial database system capable of holding, extracting, mosaicking, and fusing spatial data represented in raster- as well as in vector-format. Design aspects for this task can be specified as holding spatial data in unique data structures and providing unique access functions to the data. These are subject of this work as well as first experiences gained from the implementation of part of the extensions made for the TanDEM-X mission

The Impact of Public Research Units on Regional Innovation Processes and Regional Economic Development

It is well-known today that innovation activities of private firms play a significant role for economic growth in less-developed regions. There are many studies on these interrelations and on explaining how regional innovation processes are working and which factors are important for them. However, some important questions have still not been completely answered by these studies. One of these questions is that of the role of public research units (PRU, which include publicly financed universities and research institutes) in the process of regional innovation. There have already been several studies on the economic impacts of selected PRU on economic growth. But it is not comprehensively answered so far to what extent the impact on economic growth of a PRU is concentrated on the region where the PRU itself is located. In other words: Whether the ”knowledge transfers offered by a PRU will have more effects on firms located nearby (at a small distance from the PRU) than on firms at other locations - or if other factors than spatial distance are more important for the decision of private firms to use knowledge transfers from certain PRU. The paper presents the results of a research project for answering this question for the case of the Halle region (= the southern part of the German Land Saxony-Anhalt). It is based on an empirical analysis (two postal surveys on PRU and on knowledge-based private firms) with a focus on the most important types of knowledge transfers. For those firms which are cooperating with PRU, if it is shown that spatial distance is an important factor, in the sense that firms which are located nearer to the PRU are cooperating more intensively with the PRU than firms which are located in other regions. But also important for the firms is the import of knowledge transfers from PRU which are located outside Saxony-Anhalt. With regard to the determining factors which are important for the spatial direction of knowledge transfers, it is shown that apart from spatial proximity, also various factors on the demand side may inhibit knowledge transfers. Therefore, for being effective, regional policy should also deal with the demand side (and not just with public research units) to create better conditions for knowledge transfers in structural weak regions.

Mean-field density functional theory of a nanoconfined classical, three-dimensional Heisenberg fluid. II. The interplay between molecular packing and orientational order

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in J. Chem. Phys. 149, 054704 (2018) and may be found at https://doi.org/10.1063/1.5040934.As in Paper I of this series of papers [S. M. Cattes et al., J. Chem. Phys. 144, 194704 (2016)], we study a Heisenberg fluid confined to a nanoscopic slit pore with smooth walls. The pore walls can either energetically discriminate specific orientations of the molecules next to them or are indifferent to molecular orientations. Unlike in Paper I, we employ a version of classical density functional theory that allows us to explicitly account for the stratification of the fluid (i.e., the formation of molecular layers) as a consequence of the symmetry-breaking presence of the pore walls. We treat this stratification within the White Bear version (Mark I) of fundamental measure theory. Thus, in this work, we focus on the interplay between local packing of the molecules and orientational features. In particular, we demonstrate why a critical end point can only exist if the pore walls are not energetically discriminating specific molecular orientations. We analyze in detail the positional and orientational order of the confined fluid and show that reorienting molecules across the pore space can be a two-dimensional process. Last but not least, we propose an algorithm based upon a series expansion of Bessel functions of the first kind with which we can solve certain types of integrals in a very efficient manner.DFG, 65143814, GRK 1524: Self-Assembled Soft-Matter Nanostructures at Interface

Resolving stellar populations with crowded field 3D spectroscopy

(Abridged) We describe a new method to extract spectra of stars from observations of crowded stellar fields with integral field spectroscopy (IFS). Our approach extends the well-established concept of crowded field photometry in images into the domain of 3-dimensional spectroscopic datacubes. The main features of our algorithm are: (1) We assume that a high-fidelity input source catalogue already exists and that it is not needed to perform sophisticated source detection in the IFS data. (2) Source positions and properties of the point spread function (PSF) vary smoothly between spectral layers of the datacube, and these variations can be described by simple fitting functions. (3) The shape of the PSF can be adequately described by an analytical function. Even without isolated PSF calibrator stars we can therefore estimate the PSF by a model fit to the full ensemble of stars visible within the field of view. (4) By using sparse matrices to describe the sources, the problem of extracting the spectra of many stars simultaneously becomes computationally tractable. We present extensive performance and validation tests of our algorithm using realistic simulated datacubes that closely reproduce actual IFS observations of the central regions of Galactic globular clusters. We investigate the quality of the extracted spectra under the effects of crowding. The main effect of blending between two nearby stars is a decrease in the S/N in their spectra. The effect increases with the crowding in the field in a way that the maximum number of stars with useful spectra is always ~0.2 per spatial resolution element. This balance breaks down when exceeding a total source density of ~1 significantly detected star per resolution element. We close with an outlook by applying our method to a simulated globular cluster observation with the upcoming MUSE instrument at the ESO-VLT.Comment: accepted for publication in A&A, 19 pages, 19 figure

The Odyssey of a Polymer Chemist in Switzerland

A personal survey of some of the polymer-related work which I had the chance to carry out in Ciba-Geigy's Central Research and in the polymer departments of Ciba SC, Vantico and Huntsman is given, including a few short comments on the eventful history of the former Ciba-Geigy Central Research and Polymer Division. In the early 1970s, high-temperature-stable aromatic [polyamide – polyimide] block copolymers and the relatively easy processable bismaleimides as high-temperature thermoset materials were the dominant theme. Work on photocrosslinkable DMI polymers which ultimately led to the development of a non-silver graphic film and a presensitized negative offset printing plate was pursued at the Centre de Recherche Marly. In the field of epoxy resin chemistry, 'latent' hardeners, featuring a relatively long pot-life at room temperature and a short cure cycle at the processing temperature, were devised in the form of benzyl-sulfonium salts and imidazole-functionalized microgels. Ciba-Geigy's polymer division has pioneered the development of liquid, photoimageable soldermasks with it's Probimer® range of products. Here binderpolymers constitute the main components of the complex formulation recipes. High molecular weight polymers carrying acryloyl and carboxyl functional groups were synthesized for this purpose and have found commercial application in new soldermask generations