@article{GreueBarberkaPietschetal.1995,
  author    = {Greue, Th. and Barberka, Thomas Andreas and Pietsch, Ullrich and Stumpe, Joachim and Kauppe, G.},
  title     = {Zeitaufgel{\"o}ste Untersuchungen an Photochromen LB-Multischichten mittels energiedispersiver R{\"o}ntgenkleinwinkelstreuung, in-plane Beugung und AFM},
  year      = {1995},
  language  = {de}
}
@article{EnglischPietschReicheetal.1995,
  author    = {Englisch, Uwe and Pietsch, Ullrich and Reiche, J{\"u}rgen and Dietzel, Birgit},
  title     = {Neutronenreflektivit{\"a}t von teildeuterierten LB-Filmen mit verschiedenen Verh{\"a}ltnissen on protonierten zu deuterierten Schichten},
  year      = {1995},
  language  = {de}
}
@article{GorfmanTsirelsonPucheretal.2006,
  author    = {Gorfman, Semen and Tsirelson, Vladimir and Pucher, Andreas and Morgenroth, Wolfgang and Pietsch, Ullrich},
  title     = {X-ray diffraction by a crystal in a permanent external electric field : electric-field-induced structural response in alpha-GaPO4},
  issn      = {0108-7673},
  doi       = {10.1107/S0108767305036111},
  year      = {2006},
  abstract  = {For the first time, site-selective distortion has been investigated for two different structural units in the ternary compound alpha-GaPO4 under the influence of a permanent external electric field. Based on 54 measured reflection intensities, the electric-field-induced distortion of PO4 and GaO4 tetrahedra in alpha-GaPO4 crystals is evaluated using a model of pseudoatomic displacements introduced recently [Gorfman, Tsirelson \& Pietsch (2005). Acta Cryst. A61, 387- 396]. A stronger variation of the P-O bond lengths in the PO4 tetrahedron was found compared to the bonds in the GaO4 tetrahedron. The different distortions of the tetrahedra owing to the electric field were analysed in terms of the valence charge density of alpha-GaPO4 and its topological characteristics. The larger charge of the P pseudoatom compared to the Ga atom was recognized as the main reason for the higher sensitivity of the PO4 tetrahedron to a permanent external electric field},
  language  = {en}
}
@article{ZenSaphiannikovaNeheretal.2006,
  author    = {Zen, Achmad and Saphiannikova, Marina and Neher, Dieter and Grenzer, J{\"o}rg and Grigorian, Souren A. and Pietsch, Ullrich and Asawapirom, Udom and Janietz, Silvia and Scherf, Ullrich and Lieberwirth, Ingo and Wegner, Gerhard},
  title     = {Effect of molecular weight on the structure and crystallinity of poly(3-hexylthiophene)},
  doi       = {10.1021/Ma0521349},
  year      = {2006},
  abstract  = {Recently, two different groups have reported independently that the mobility of field-effect transistors made from regioregular poly(3-hexylthiophene) (P3HT) increases strongly with molecular weight. Two different models were presented: one proposing carrier trapping at grain boundaries and the second putting emphasis on the conformation and packing of the polymer chains in the thin layers for different molecular weights. Here, we present the results of detailed investigations of powders and thin films of deuterated P3HT fractions with different molecular weight. For powder samples, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) were used to investigate the structure and crystallization behavior of the polymers. The GPC investigations show that all weight fractions possess a rather broad molecular weight distribution. DSC measurements reveal a strong decrease of the crystallization temperature and, most important, a significant decrease of the degree of crystallinity with decreasing molecular weight. To study the structure of thin layers in lateral and vertical directions, both transmission electron microscopy (TEM) and X-ray grazing incidence diffraction (GID) were utilized. These methods show that thin layers of the low molecular weight fraction consist of well-defined crystalline domains embedded in a disordered matrix. We propose that the transport properties of layers prepared from fractions of poly(3-hexylthiophene) with different molecular weight are largely determined by the crystallinity of the samples and not by the perfection of the packing of the chains in the individual crystallites},
  language  = {en}
}