Untersuchung der Struktur und Dynamik der Rekonstruktion der Molybdaen(001)-Oberflaeche mit hochaufloesender Helium-Atomstrahlstreuung

SIGLEAvailable from TIB Hannover: DW 9584 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Nanocomposite characterization on multiple length scales using microSAXS

Nanocomposites have great potential for the rational synthesis of tailored materials. However, the templating process that transfers the self-organized nanostructure of a block copolymer or other mesophase onto the functional material is by no means trivial, and often involves multiple steps, each of which presents its own chemical and physical challenges. As a result the nanocomposite may not be homogeneous, but can be phase-separated into various components which may feature their own specific microstructure. Here it is shown how scanning microbeam small-angle X-ray scattering (µSAXS) can be used to characterize a thermoset resol/poly(isoprene-block-ethylene oxide) nanocomposite on multiple length scales with respect to homogeneity and microphase separation

X-ray diffraction study of a semiconductor/electrolyte interface: n-GaAs(001)/H₂SO₄(:Cu)

We used X-ray diffraction to investigate the n-GaAs(001)0.5M H2SO4 interface in-situ under potential control in a three-electrode, thin-layer electrochemical cell. The intensity of crystal truncation rods as a function of the electrode potential was recorded. A pronounced increase in surface roughness was proven by the strong decrease in the rod intensities with time at an electrode potential of −0.6 V versus SCE. Surprisingly, this process could be partially reversed at more negative potentials (< −0.9 V versus SCE). Possible mechanisms explaining these observations are discussed. After the deposition of Cu from a 0.5M H2SO41mM CuSO4 solution, three-dimensional, epitaxially grown Cu islands with several degree mosaic spread were observed

Untersuchung der Struktur und Dynamik der Rekonstruktion der Molybdaen(001)-Oberflaeche mit hochaufloesender Helium-Atomstrahlstreuung

SIGLEAvailable from TIB Hannover: RA 1396(1991,6) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

On the effect of confinement on the structure and properties of small-molecular organic semiconductors

Many typical organic optoelectronic devices, such as light-emitting diodes, field-effect transistors, and photovoltaic cells, use an ultrathin active layer where the organic semiconductor is confined within nanoscale dimensions. However, the question of how this spatial constraint impacts the active material is rarely addressed, although it may have a drastic influence on the phase behavior and microstructure of the active layer and hence the final performance. Here, the small-molecule semiconductor p-DTS(FBTTh2)2 is used as a model system to illustrate how sensitive this class of material can be to spatial confinement on device-relevant length scales. It is also shown that this effect can be exploited; it is demonstrated, for instance, that spatial confinement is an efficient tool to direct the crystal orientation and overall texture of p-DTS(FBTTh2)2 structures in a controlled manner, allowing for the manipulation of properties including photoluminescence and charge transport characteristics. This insight should be widely applicable as the temperature/confinement phase diagrams established via differential scanning calorimetry and grazing-incidence X-ray diffraction are used to identify specific processing routes that can be directly extrapolated to other functional organic materials, such as polymeric semiconductors, ferroelectrics or high-refractive-index polymers, to induce desired crystal textures or specific (potentially new) polymorphs