Publications by authors named "Thomas Ules"

Structured surfaces, which are the basis of the lotus blossom effect, have great potential to serve/operate as functionalised surfaces, i.e., surfaces with specific and/or adjustable properties.

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The touch-feel sensation of product surfaces arouses growing interest in various industry branches. To entangle the underlying physical and material parameters responsible for a specific touch-feel sensation, a new measurement system has been developed. This system aims to record the prime physical interaction parameters at a time, which is considered a necessary prerequisite for a successful physical description of the haptic sensation.

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The present work provides a comparative study on the photopatterning of epoxy-based thermosets as a function of network structure and network mobility. Local switching of solubility properties by light of a defined wavelength is achieved by exploiting versatile -nitrobenzyl ester (-NBE) chemistry. -NBE derivatives with terminal epoxy groups are synthetized and thermally cured with different types of cycloaliphatic anhydrides via nucleophilic ring opening reaction.

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It is becoming accepted that ultrathin dielectric layers on metals are not merely passive decoupling layers, but can actively influence orbital energy level alignment and charge transfer at interfaces. As such, they can be important in applications ranging from catalysis to organic electronics. However, the details at the molecular level are still under debate.

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The frontier orbitals of molecules are the prime determinants of their chemical, optical and electronic properties. Arguably, the most direct method of addressing the (filled) frontier orbitals is ultra-violet photoemission spectroscopy (UPS). Although UPS is a mature technique from the early 1970s on, the angular distribution of the photoemitted electrons was thought to be too complex to be analysed .

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The basis for a quantum-mechanical description of matter is electron wave functions. For atoms and molecules, their spatial distributions and phases are known as orbitals. Although orbitals are very powerful concepts, experimentally only the electron densities and -energy levels are directly observable.

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Porphyrin molecules, of interest as versatile materials for organic electronics, are highly prone to formation of significantly different polymorphic phases. To elucidate the determinants for the specific polymorphic phase formed in thin films as well as for the arrangement of the molecules on a given substrate two different anisotropic substrate surfaces have been selected: KCl(100) and the oxygen reconstructed Cu(110) surface. We observe that the crystal structure of the thin films depends on the substrate, whereas the relative molecular orientations in both cases are similar.

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The formation of crystalline para-sexiphenyl (6P) films on Cu(110) and Cu(110)-(2 × 1)O (Cu-O) has been studied by low energy electron diffraction, X-ray absorption spectroscopy and both in situ and ex situ X-ray diffraction methods to elucidate the transition from the initial monolayers to crystalline thin films. It is found that, for Cu-O, a single and, for Cu(110), a double wetting layer is formed which then acts as a template for the subsequent 3D crystal growth. For both substrates the orientation of the long molecular axes of the 6P molecules in the first layers is conserved for the molecules in the bulk crystals growing on them.

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This study investigates epitaxially oriented pentacene films grown on Cu(110) surfaces crystallizing either in the "thin film" phase with standing molecules or in the "single crystal" structure with molecules lying with their long axes parallel to the substrate.

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Well-ordered and oriented monolayers of conjugated organic molecules can offer new perspectives on surface bonding. We will demonstrate the importance of the momentum distribution, or symmetry, of the adsorbate molecules' π orbitals in relation to the states available for hybridization at the metal surface. Here, the electronic band structure of the first monolayer of sexiphenyl on Cu(110) has been examined in detail with angle-resolved ultraviolet photoemission spectroscopy over a large momentum range and will be compared to measurements of a multilayer thin film and to density functional calculations.

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Pre-nucleation dynamics, nucleation and templated self-assembly of a conjugated planar aromatic molecule are investigated by photoemission electron microscopy (PEEM). The high resolution of individual molecular layers in PEEM, in combination with a numerical simulation, reveals the dynamic behaviour of molecules during the pre-nucleation deposition period and their temperature dependence. The in situ deposition of p-sexiphenyl (6P) molecules on Cu(110) and Cu(110) 2 × 1-O surfaces in ultrahigh vacuum, when monitored by PEEM in real-time allows (a) layer densities, (b) meta-stable layer filling by 6P molecules, (c) dynamic surface redistributions during layer filling and (d) critical density spontaneous dewetting to be accurately measured.

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