@article{PietschMukhopadhyaySanyaletal.2004,
  author    = {Pietsch, Ullrich and Mukhopadhyay, M. K. and Sanyal, M. K. and Datta, A. and Mukherjee, M. and Geue, Thomas and Grenzer, J{\"o}rg},
  title     = {Transition from two-dimensional to three-dimensional melting in Langmuir-Blodgett films},
  year      = {2004},
  abstract  = {Results of energy-dispersive x-ray reflectivity and grazing incidence diffraction studies of Langmuir-Blodgett films exhibited evolution of conventional three-dimensional melting from continuous melting, characteristic of two- dimensional systems, as a function of deposited monolayers. Continuous expansion followed by a sharp phase transition of the in-plane lattice was observed before the melting point and found to be independent of number of deposited layers. Evolution of conventional melting with an increase in the number of monolayers could be quantified by measuring stiffness against tilting of the vertical stack of molecules, which are kept together by an internal field. The internal field as defined in this model reduces as the in-plane lattice expands and the sample temperature approaches melting point. The sharpness of the melting transition, which has been approximated by a Langevin function, increases with the number of deposited monolayers},
  language  = {en}
}
@article{Pietsch2003,
  author    = {Pietsch, Ullrich},
  title     = {Thin Layers of columns of an amphiphilic hexa-peri-hexabenzocoronene at silicon wafer surfaces},
  year      = {2003},
  language  = {en}
}
@article{EnglischGutberletSeitzetal.1997,
  author    = {Englisch, Uwe and Gutberlet, T. and Seitz, R. and Oeser, R. and Pietsch, Ullrich},
  title     = {Thermally induced rearrangement of fatty acid salt molecules in Langmuir-Blodgett multilayers},
  year      = {1997},
  language  = {en}
}
@article{PietschGrigorianGrenzeretal.2003,
  author    = {Pietsch, Ullrich and Grigorian, Souren A. and Grenzer, J{\"o}rg and Vartanyants, Ivan A.},
  title     = {Thermal diffuse scattering in grazing incidence diffraction},
  year      = {2003},
  language  = {en}
}
@article{SiebrechtSchreyerEnglischetal.1997,
  author    = {Siebrecht, R. and Schreyer, A. and Englisch, Uwe and Pietsch, Ullrich and Zabel, Hartmut},
  title     = {The new reflectometer ADAM at the ILL},
  year      = {1997},
  language  = {en}
}
@article{PietschGrenzerGeueetal.2001,
  author    = {Pietsch, Ullrich and Grenzer, J{\"o}rg and Geue, Thomas and Neißendorfer, Frank and Brezesinski, Gerald and Symietz, Christian and M{\"o}hwald, Helmuth and Gudat, Wolfgang},
  title     = {The energy dispersive reflectometer at BESSY II : a challenge for thin film analysis},
  issn      = {0167- 5087},
  year      = {2001},
  language  = {en}
}
@article{PietschDavaasambuuKochinetal.2004,
  author    = {Pietsch, Ullrich and Davaasambuu, Jav and Kochin, V. and Schwarz, K. H. and Blaha, Pawel},
  title     = {The atomistic origin of the inverse piezoelectric effect in a-quartz},
  year      = {2004},
  abstract  = {Ab initio calculations have been carried out using the FP-APW+lo method in order to understand the atomic origin of the inverse piezoelectric effect in x-quartz. The external electric field was modelled by a saw-like potential V-ext in order to achieve translational symmetry within a supercell (SC) containing 72 atoms. The original trigonal quartz structure was repeated along the [110] direction, which corresponds to the direction of the external field. An electric field with 550 kV/mm was applied and the atomic positions of the SC were relaxed until the forces acting on the atoms vanished. In parts of the SC, V-ext changes almost linearly and thus the relaxed atomic positions can be used to determine the structural response due to the external electric field. The calculations provide the piezoelectric modulus of the correct order of magnitude. In contrast to previous models and in agreement with recent experimental results, the atomic origin of the piezoelectric effect can be described by a rotation of slightly deformed SiO4 tetrahedra against each other. The change of the Si-O bond lengths and the tetrahedral O-Si-O angles is one order of magnitude smaller than that of the Si-O-Si angles between neighbouring tetrahedra. The calculated changes of X-ray structure factors are in agreement with experiment when the theoretical data are extrapolated down to the much smaller field strength that is applied in the experiment (E < 10 kV/mm). (C) 2004 Elsevier Ltd. All rights reserved},
  language  = {en}
}
@article{MukherjeeBhattacharyaSanyaletal.2000,
  author    = {Mukherjee, M. and Bhattacharya, M. K. and Sanyal, M. K. and Geue, Thomas and Grenzer, J{\"o}rg and Pietsch, Ullrich},
  title     = {Temperature dependent thickness and surface tension of polymer films},
  isbn      = {81-7371295-6},
  year      = {2000},
  language  = {en}
}
@article{BrajpuriyaTripathiSharmaetal.2007,
  author    = {Brajpuriya, Ranjeet and Tripathi, Sumit and Sharma, Abhishek and Chaudhari, S.M. and Phase, D.M. and Gupta, Ajay and Shripathi, Thoudinja and Leitenberger, Wolfram and Pietsch, Ullrich and Laxmi, N.},
  title     = {Temperature dependent energy-dispersive X-ray diffraction and magnetic study of Fe/Al interface},
  issn      = {0169-4332},
  doi       = {10.1016/j.apsusc.2007.04.069},
  year      = {2007},
  abstract  = {In situ temperature dependent energy-dispersive structural and magnetic study of electron beam evaporated Fe/Al multilayer sample (MLS) has been investigated. The structural studies show the formation of an intermixed FeAl transition layer of a few nanometers thick at the interface during deposition, which on annealing at 300 degrees C transforms to B2FeAl intermetallic phase. Magnetization decreases with increase in temperature and drops to minimum above 300 degrees C due to increase in anti-ferromagnetic interlayer coupling and formation of nonmagnetic FeAl phase at the interface. The Curie temperature (T-c) is found to be 288 degrees C and is much less than that of bulk bcc Fe.},
  language  = {en}
}
@article{BodenthinGrenzerLauteretal.2002,
  author    = {Bodenthin, Yves and Grenzer, J{\"o}rg and Lauter, Robert and Pietsch, Ullrich and Lehmann, Pit and Kurth, Dirk G. and M{\"o}hwald, Helmuth},
  title     = {Temperature and time resolved x-ray scattering at thin organic films},
  year      = {2002},
  language  = {en}
}
@article{BolmEnglischPenacoradaetal.1997,
  author    = {Bolm, A. and Englisch, Uwe and Penacorada, Florencio and Gerstenberger, M. and Pietsch, Ullrich},
  title     = {Temperature and time dependent investigations of cd- and uranyl-stearate multilayers by means of neutron reflectivity measurements},
  year      = {1997},
  language  = {en}
}
@article{MukhopadhyayDattaSanyaletal.2001,
  author    = {Mukhopadhyay, M. K. and Datta, A. and Sanyal, M. K. and Geue, Thomas and Pietsch, Ullrich},
  title     = {Synchrotron Studies of Melting of Langmuir-Blodgett Films},
  year      = {2001},
  language  = {en}
}
@article{PietschPanznerPfeifferetal.2005,
  author    = {Pietsch, Ullrich and Panzner, Tobias and Pfeiffer, Franz and Robinson, Ian K.},
  title     = {Substrate morphology repetition in "thick" polymer films},
  year      = {2005},
  abstract  = {Using Grazing-incidence small-angle scattering (GISAXS) technique we investigated the surface morphology of polymer films spin-coated on different silicon substrates. As substrates we used either technologically smooth silicon wafers or the same silicon wafer coated with thin aluminium or gold films which show a granular structure at the surface. Although the polymer thickness exceeds 300 nm the GISAXS pattern of the film shows the same in-plane angle distribution Delta2theta as the underlying substrate. Annealing the polymer films at a temperature above its glass transition temperature Delta2theta changed from a broad to a narrow distribution as it is typically for films on pure silicon. The experiment can be interpreted by roughness replication and density fluctuation within the polymer film created while spin-coating at room temperature. Due to the low segment mobility there are density fluctuations which repeat the surface morphology of the substrate. Above the glass temperature the polymer density can be homogenized independently from the morphology of the substrate. (C) 2004 Elsevier B.V. All rights reserved},
  language  = {en}
}
@article{AbboudSendPashniaketal.2013,
  author    = {Abboud, Ali and Send, Sebastian and Pashniak, N. and Leitenberger, Wolfram and Ihle, Sebastian and Huth, M. and Hartmann, Robert and Str{\"u}der, Lothar and Pietsch, Ullrich},
  title     = {Sub-pixel resolution of a pnCCD for X-ray white beam applications},
  series = {Journal of instrumentation},
  volume    = {8},
  journal   = {Journal of instrumentation},
  number    = {3},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {1748-0221},
  doi       = {10.1088/1748-0221/8/05/P05005},
  pages     = {17},
  year      = {2013},
  abstract  = {A new approach to achieve sub-pixel spatial resolution in a pnCCD detector with 75 x 75 mu m(2) pixel size is proposed for X-ray applications in single photon counting mode. The approach considers the energy dependence of the charge cloud created by a single photon and its split probabilities between neighboring pixels of the detector based on a rectangular model for the charge cloud density. For cases where the charge of this cloud becomes distributed over three or four pixels the center position of photon impact can be reconstructed with a precision better than 2 mu m. The predicted charge cloud sizes are tested at selected X-ray fluorescence lines emitting energies between 6.4 keV and 17.4 keV and forming charge clouds with size (rms) varying between 8 mu m and 10 mu m respectively. The 2 mu m enhanced spatial resolution of the pnCCD is verified by means of an x-ray transmission experiment throughout an optical grating.},
  language  = {en}
}
@article{ReicheKnochenhauerDieteletal.1997,
  author    = {Reiche, J{\"u}rgen and Knochenhauer, Gerald and Dietel, Reinhard and Freydank, Anke-Christine and Zetzsche, Thomas and Pietsch, Ullrich and Brehmer, Ludwig and Barberka, Thomas Andreas and Geue, Thomas},
  title     = {Structure of thermally treated oxadiazoleamide Langmuir-Blodgett films},
  year      = {1997},
  abstract  = {The thermal treatment of Y-type Langmuir-Blodgett (LB) films formed from the amphiphilic derivative of 2,5- diphenyl-1,3,4-oxadiazole 1 results in changes of the molecular packing. These changes have been analysed by a combination of X-ray specular reflectivity data, X-ray grazing incidence diffraction data and scanning force microscopy images, On the basis of these experimental data we have simulated possible supramolecular structures, These simulations provide insight into the intermolecular interactions giving rise to the observed structural transitions. The crystalline structure induced by thermal treatment of the LB films is characterized by a uniaxial texture, which is correlated with the dipping direction during deposition of the LB film.},
  language  = {en}
}
@article{PietschBodenthinGrenzeretal.2005,
  author    = {Pietsch, Ullrich and Bodenthin, Yves and Grenzer, J{\"o}rg and Geue, Thomas and M{\"o}hwald, Helmuth and Kurth, Dirk G.},
  title     = {Structure and temperature behavior of metallo-supramolecular assemblies},
  year      = {2005},
  abstract  = {A detailed structural analysis of a Langmuir-Blodgett (LB) multilayer composed of a polyelectrolyte-amphiphile complex (PAC) is presented. The PAC is self-assembled from metal ions, ditopic bis-terpyridines, and amphiphiles. The vertical structure of the LB multilayer is investigated by X-ray reflectometry. The multilayer has a periodicity of 57 A, which corresponds to an architecture of flat lying metallo-supramolecular coordination polyelectrolyte (MEPE) rods and upright-standing amphiphiles (dihexadecyl phosphate, DHP). In-plane diffraction reveals hexagonal packing of the DHP molecules. Using extended X-ray absorption fine structure (EXAFS) experiments, we prove that the central metal ion is coordinated to the terpyridine moieties in a pseudo-octahedral coordination environment. The Fe-N bond distances are 1.82 and 2.0 angstrom, respectively. Temperature resolved measurements indicate a reversible phase transition in a temperature range up to 55 degrees C. EXAFS measurements indicate a lengthening of the average Fe-N bond distance from 1.91 to 1.95 angstrom. The widening of the coordination cage upon heating is expected to lower the ligand field stabilization, thus giving rise to spin transitions in these composite materials},
  language  = {en}
}
@article{PietschGuptaPauletal.2004,
  author    = {Pietsch, Ullrich and Gupta, Amod and Paul, A. and Meneghini, C. and Mibu, K. and Maddalena, S. and Dal Toe, S. and Principi, G.},
  title     = {Structural characterization of epitaxial Fe/Cr multilayers using anomalous x-ray scattering and neutron reflectivity},
  year      = {2004},
  abstract  = {The interface structure of epitaxial Fe/Cr multilayers was studied using anomalous X-ray and neutron reflectivity. The analysis of X-ray reflectivity at three different energies provided a reliable information about the interface roughnesses. It is found that the Cr-on-Fc interface is more diffused as compared to the Fe-on-Cr interface and that the roughness exhibits a significant increase with increasing depth. The magnetic roughness, as determined from neutron reflectivity, is lower than the geometrical roughness, in conformity with the behavior of a number of magnetic thin films and multilayers. (C) 2004 Elsevier B.V. All rights reserved},
  language  = {en}
}
@article{DarowskiPaschkePietschetal.1998,
  author    = {Darowski, Nora and Paschke, K. and Pietsch, Ullrich and Wang, K. H. and Forchel, Alfred and L{\"u}bbert, Daniel and Baumbach, Tilo},
  title     = {Structural characterization of a GaAs surface wire structure by triple-axis X-ray grazing incidence diffraction},
  year      = {1998},
  language  = {en}
}
@article{ZhuangSchellingStangletal.2000,
  author    = {Zhuang, Y. and Schelling, Christoph and Stangl, Jochen and Penn, C. and Senz, S. and Sch{\"a}ffler, Friedrich and Roche, T. and Daniel, A. and Grenzer, J{\"o}rg and Pietsch, Ullrich and Bauer, G{\"u}nther},
  title     = {Structural and optical properties of Si/Si{1-x}Ge{x} wires},
  year      = {2000},
  language  = {en}
}
@article{ZhuangHolyStangletal.1999,
  author    = {Zhuang, Y. and Hol{\´y}, V{\´a}clav and Stangl, Jochen and Darhuber, A. and Mikulik, P. and Zerlauth, S. and Sch{\"a}ffler, F. and Bauer, G{\"u}nther and Darowski, Nora and L{\"u}bbert, Daniel and Pietsch, Ullrich},
  title     = {Strain relaxation in periodic arrays of Si/SiGe quantum wires determined by coplanar high-resolution x-ray diffrcation and grazing-incidence diffraction},
  year      = {1999},
  language  = {en}
}
@article{LuebbertBaumbachPontietal.1999,
  author    = {L{\"u}bbert, Daniel and Baumbach, Tilo and Ponti, S. and Pietsch, Ullrich and Leprince, L. and Schneck, J. and Talneau, A.},
  title     = {Strain investigation of low strained buried gratings by grazing incidence X-Ray diffraction and the theory of elasticity},
  year      = {1999},
  language  = {en}
}
@article{PietschZeimerHofmannetal.2001,
  author    = {Pietsch, Ullrich and Zeimer, Ute and Hofmann, L. and Grenzer, J{\"o}rg and Gramlich, S.},
  title     = {Strain induced compositional modulations in AlGaAs overlayers induced by lateral surface gratings},
  issn      = {0272-9172},
  year      = {2001},
  language  = {en}
}
@article{GrenzerDarowskiGeueetal.2001,
  author    = {Grenzer, J{\"o}rg and Darowski, Nora and Geue, Thomas and Pietsch, Ullrich and Daniel, A. and Rennon, Siegfried and Reithmaier, Johann-Peter and Forchel, Alfred},
  title     = {Strain analysis and quantum well intermixing of a laterally modulated multiquantum well system produced by focused ion beam implantation},
  year      = {2001},
  language  = {en}
}
@article{HennebergPietschPanzneretal.2006,
  author    = {Henneberg, Oliver and Pietsch, Ullrich and Panzner, Tobias and Geue, Thomas and Finkelstein, Kenneth D.},
  title     = {Simultaneous X-ray and visible light diffraction for the investigation of surface relief and density grating formation in azobenzene containing polymer films},
  issn      = {1542-1406},
  doi       = {10.1080/15421400500383345},
  year      = {2006},
  abstract  = {The development of surface relief and density patterns in azobenzene polymer films was studied by diffraction at two different wavelengths. We used x-ray diffraction of synchrotron radiation at 0.124 nm in combination with visible light diffraction at a wavelength of 633 nm. In contrast to visible light scattering x-ray diffraction allows the separation of a surface relief and a density grating contribution due to the different functional dependence of the scattering power. Additionally, the x-ray probe is most sensitive for the onset of the surface grating formation},
  language  = {en}
}
@article{VeldkampErkoGudatetal.1999,
  author    = {Veldkamp, Markus and Erko, Alexei and Gudat, Wolfgang and Abrosimov, Nikolai V. and Alex, Volker and Khasanov, Salavat and Neissendorfer, Frank and Pietsch, Ullrich and Shekhtman, Veniamin},
  title     = {Si(1-x)Ge(x) laterally graded crystals as monochromators for X-Ray absorption spectroscopy studies},
  year      = {1999},
  language  = {en}
}
@article{AvilovKulyginPietschetal.1999,
  author    = {Avilov, Anatoly S. and Kulygin, Alexander K. and Pietsch, Ullrich and Spence, John C. H. and Tsirelson, Vladimir G. and Zuo, Ming J.},
  title     = {Scanning system for high-energy electron diffractometry},
  issn      = {0021-8898},
  doi       = {10.1107/S0021889899006755},
  year      = {1999},
  language  = {en}
}
@article{PietschHazraChinietal.2004,
  author    = {Pietsch, Ullrich and Hazra, S. and Chini, T. K. and Sanyal, M. K. and Grenzer, J{\"o}rg},
  title     = {Ripple structure of crystalline layers in ion beam induced Si wafers},
  year      = {2004},
  abstract  = {Ion-beam-induced ripple formation in Si wafers was studied by two complementary surface sensitive techniques, namely atomic force microscopy (AFM) and depth-resolved x-ray grazing incidence diffraction (GID). The formation of ripple structure at high doses (similar to7x10(17) ions/cm(2)), starting from initiation at low doses (similar to1x10(17) ions/cm(2)) of ion beam, is evident from AFM, while that in the buried crystalline region below a partially crystalline top layer is evident from GID study. Such ripple structure of crystalline layers in a large area formed in the subsurface region of Si wafers is probed through a nondestructive technique. The GID technique reveals that these periodically modulated wavelike buried crystalline features become highly regular and strongly correlated as one increases the Ar ion-beam energy from 60 to 100 keV. The vertical density profile obtained from the analysis of a Vineyard profile shows that the density in the upper top part of ripples is decreased to about 15\% of the crystalline density. The partially crystalline top layer at low dose transforms to a completely amorphous layer for high doses, and the top morphology was found to be conformal with the underlying crystalline ripple},
  language  = {en}
}
@article{Pietsch2002,
  author    = {Pietsch, Ullrich},
  title     = {Reversible negative thermal expansion of polymer films},
  year      = {2002},
  language  = {en}
}
@article{TsirelsonAvilovLepeshovetal.2001,
  author    = {Tsirelson, Vladimir G. and Avilov, Anatoly S. and Lepeshov, G. G. and Kuligin, A. K. and Stahn, Jochen and Pietsch, Ullrich and Spence, J. C. H.},
  title     = {Quantitative Analysis of the Inner-Crystal Electrostatic Potential of several Rock-Salt-Structure Crystals Using Accurate Electron-Diffraction Data},
  issn      = {1089-5647},
  year      = {2001},
  language  = {en}
}
@article{GeueStumpePietschetal.1995,
  author    = {Geue, Thomas and Stumpe, Joachim and Pietsch, Ullrich and Haak, M. and Kaupp, G.},
  title     = {Photochemically induced changes of optical anisotropy and surface of LB-multilayers built up by an amphiphilic and liquid crystalline copolymer conating azobenzene moieties},
  year      = {1995},
  language  = {en}
}
@article{ZeimerPietschGrenzeretal.2005,
  author    = {Zeimer, Ute and Pietsch, Ullrich and Grenzer, Joerg and Fricke, J. and Knauer, A. and Weyers, Markus},
  title     = {Optimised two layer overgrowth of a lateral strain-modulated nanostructure},
  issn      = {0925-8388},
  year      = {2005},
  abstract  = {Recently it has been shown that lateral carrier confinement in an InGaAs quantum well (QW) embedded in GaAs can be achieved by using a laterally patterned InGaP stressor layer on top of the heterostructure. To exploit this effect in a device the structure has to be planarized by a second epitaxial step. It has been shown that the lateral strain modulation almost vanishes after overgrowth with GaAs, whereas overgrowth with a single ternary layer of opposite strain compared to the stressor layer suffers from strain induced decomposition. Here we show that the lateral carrier confinement of the initially free standing nanostructure can almost be maintained using a two step process for overgrowth, where a strained thin ternary layer is grown first followed by GaAs up to complete planarization of the patterned structure. Thickness and composition of the ternary layer are adjusted on the basis of finite element calculations of the strain distribution (FEM). The strain field achieved after overgrowth is probed by X-ray grazing- incidence diffraction (GID). (c) 2005 Elsevier B.V. All rights reserved},
  language  = {en}
}
@article{SaphiannikovaHennebergGeneetal.2004,
  author    = {Saphiannikova, Marina and Henneberg, Oliver and Gene, T. M. and Pietsch, Ullrich and Rochon, Paul},
  title     = {Nonlinear effects during inscription of azobenzene surface relief gratings},
  issn      = {1520-6106},
  year      = {2004},
  abstract  = {Surface relief gratings were inscribed on azobenzene polymer films using a pulselike exposure of an Ar+ laser. The inscription process was initiated by a sequence of short pulses followed by much longer relaxation pauses. The development of the surface relief grating was probed by a He-Ne laser measuring the scattering intensity of the first- order grating peak. The growth time of the surface relief grating was found to be larger than the length of the pulses used. This unusual behavior can be considered as a nonlinear material response associated with the trans-cis isomerization of azobenzene moieties. In this study the polymer stress was assumed to be proportional to the number of cis-isomers. One-dimensional viscoelastic analysis was used to derive the polymer deformation. The rate of trans-cis isomerization increases with the intensity of the inscribing light; in the dark it is equal to the rate of thermal cis- trans isomerization. The respective relaxation times were estimated by fitting theoretical deformation curves to experimental data},
  language  = {en}
}
@article{DarowskiPietschZeimeretal.1998,
  author    = {Darowski, Nora and Pietsch, Ullrich and Zeimer, Ute and Smirnitzki, V. and Bugge, F.},
  title     = {Nondestructive analysis of a lateral GaAs nanostructure buried under AlGaAs using conventional high resolution and grazing incidence X-ray diffraction},
  year      = {1998},
  language  = {en}
}
@article{PietschSaphiannikovaHennebergetal.2004,
  author    = {Pietsch, Ullrich and Saphiannikova, Marina and Henneberg, Oliver and Geue, Thomas},
  title     = {Non-linear effects during inscription of azobenzene surface relief gratings},
  year      = {2004},
  language  = {en}
}
@article{PietschGrenzerGrigorianetal.2004,
  author    = {Pietsch, Ullrich and Grenzer, J{\"o}rg and Grigorian, Souren A. and Weyers, Markus and Zeimer, Ute and Feranchuk, S. and Fricke, J. and Kissel, H. and Knauer, A. and Tr{\"a}nkle, G.},
  title     = {Nanoengineering of lateral strain-modulation in quantum well heterostructures},
  year      = {2004},
  abstract  = {We have developed a method to design a lateral band-gap modulation in a quantum well heterostructure. The lateral strain variation is induced by patterning of a stressor layer grown on top of a single quantum well which itself is not patterned. The three-dimensional (3D) strain distribution within the lateral nanostructure is calculated using linear elasticity theory applying a finite element technique. Based on the deformation potential approach the calculated strain distribution is translated into a local variation of the band-gap energy. Using a given vertical layer structure we are able to optimize the geometrical parameters to provide a nanostructure with maximum lateral band-gap variation. Experimentally such a structure was realized by etching a surface grating into a tensile-strained InGaP stressor layer grown on top of a compressively strained InGaAs-single quantum well. The achieved 3D strain distribution and the induced band-gap variation are successfully probed by x-ray grazing incidence diffraction and low-temperature photoluminescence measurements, respectively},
  language  = {en}
}
@article{AvilovLepeshovPietschetal.2001,
  author    = {Avilov, Anatoly S. and Lepeshov, G. G. and Pietsch, Ullrich and Tsirelson, Vladimir G.},
  title     = {Multipole analysis of the electron density and electrostatic potential in Germanium by high-resolution electron diffraction},
  issn      = {0022-3697},
  year      = {2001},
  language  = {en}
}
@article{ReichePenacoradaGeueetal.1997,
  author    = {Reiche, J{\"u}rgen and Penacorada, Florencio and Geue, Thomas and Pietsch, Ullrich and Brehmer, Ludwig},
  title     = {Monolayers and multilayers of uranyl arachidate : in-plane structure of uranyl arachidate multilayers},
  year      = {1997},
  abstract  = {The molecular in-plane structure of uranyl arachidate Langmuir-Blodgett (LB) films formed at different subphase pH values was analysed by means of X-ray grazing-incidence diffraction. For multilayers formed at low subphase pH a reorganisation of the arachidic acid film structure is confirmed. At appropriate subphase pH values, reorganisation of the film structure, e.g. via the formation of three-dimensional crystallites, is prevented by the presence of the uranyl ions and by the subsequent introduction of conformational disorder (gauche defects) in the alkyl chains. The observation of a macroscopic flow-induced in-plane texture in these uranyl arachidate LB films has profound implications for the design of ordered, supramolecular structures by the Langmuir-Blodgett technique.},
  language  = {en}
}
@article{SaphiannikovaGeueHennebergetal.2004,
  author    = {Saphiannikova, Marina and Geue, Thomas and Henneberg, Oliver and Morawetz, Knut and Pietsch, Ullrich},
  title     = {Linear viscoelastic analysis of formation and relaxation of azobenzene polymer gratings},
  doi       = {10.1063/1.1642606},
  year      = {2004},
  abstract  = {Surface relief gratings on azobenzene containing polymer films were prepared under irradiation by actinic light. Finite element modeling of the inscription process was carried out using linear viscoelastic analysis. It was assumed that under illumination the polymer film undergoes considerable plastification, which reduces its original Young's modulus by at least three orders of magnitude. Force densities of about 10(11) N/m(3) were necessary to reproduce the growth of the surface relief grating. It was shown that at large deformations the force of surface tension becomes comparable to the inscription force and therefore plays an essential role in the retardation of the inscription process. In addition to surface profiling the gradual development of an accompanying density grating was predicted for the regime of continuous exposure. Surface grating development under pulselike exposure cannot be explained in the frame of an incompressible fluid model. However, it was easily reproduced using the viscoelastic model with finite compressibility. (C) 2004 American Institute of Physics},
  language  = {en}
}
@article{ReicheDietzelFreydanketal.1995,
  author    = {Reiche, J{\"u}rgen and Dietzel, Birgit and Freydank, Anke-Christine and Geue, Thomas and Pietsch, Ullrich and Brehmer, Ludwig},
  title     = {Lateral structure of thermally treated oxadiazole Langmuir-Blodgett films},
  year      = {1995},
  language  = {en}
}
@article{HolyStanglZerlauthetal.1999,
  author    = {Hol{\´y}, V{\´a}clav and Stangl, Jochen and Zerlauth, S. and Bauer, G{\"u}nther and Darowski, Nora and L{\"u}bbert, Daniel and Pietsch, Ullrich},
  title     = {Lateral arrangement of self-assembled quantum dots in an SiGe/Si superlattice},
  year      = {1999},
  language  = {en}
}
@article{PietschGuptaGuptaetal.2004,
  author    = {Pietsch, Ullrich and Gupta, Ajay and Gupta, Mukul and Ayachit, S. and Rajagopalan, S. and Balamurgan, A. K. and Tyagi, A. K.},
  title     = {Iron self-diffusion in nanocrystalline FeCr thin films},
  year      = {2004},
  abstract  = {Thin films of amorphous Fe85Zr15 alloy were deposited by ion-beam sputtering of a composite target. Analogous to the melt-spun amorphous alloys of similar composition, the crystallization of the amorphous film occurs in two steps, however, with a substantially reduced thermal stability. After completion of the first crystallization step which starts at 473 K, the microstructure consists of 12 nm nanocrystals of bcc-Fe embedded in a grain boundary region of the remaining amorphous phase. At 673 K, the remaining amorphous phase transforms into the Fe2Zr alloy. The self-diffusion measurements of iron in the nanocrystalline state and in the parent amorphous state has been carried out using secondary ion mass spectroscopy (SIMS) depth profiling and neutron reflectivity techniques. In contrast to the case of finemet Fe73.5Si13.5B9Nb3Cu1 alloy, where a significant enhancement of diffusivity takes place in the nanocrystalline state, in the present case the diffusivity in the nanocrystalline state is similar to that in the parent amorphous state. It is suggested that in this system the atomic diffusion occurs mainly via the grain boundary regions. The calculated values of the pre-exponential factor and the activation energy for the diffusion are D-0 = 1 x 10(-14+/-1) m(2)/s and E = (0.7 +/- 0.1) eV respectively. (C) 2004 Published by Elsevier B.V.},
  language  = {en}
}
@article{Pietsch2000,
  author    = {Pietsch, Ullrich},
  title     = {Investigations of semiconductor surfaces and interfaces by X-ray grazing incidence diffraction},
  issn      = {0011-3891},
  year      = {2000},
  language  = {en}
}
@article{EnglischPenacoradaSamoilenkoetal.1998,
  author    = {Englisch, Uwe and Penacorada, Florencio and Samoilenko, I. and Pietsch, Ullrich},
  title     = {Investigation of the vertical molecular exchange in a complex organic multilayer system},
  year      = {1998},
  language  = {en}
}
@article{UlyanenkovBaumbachDarowskietal.1999,
  author    = {Ulyanenkov, A. and Baumbach, Tilo and Darowski, Nora and Pietsch, Ullrich and Wang, K. H. and Forchel, Alfred and Wiebach, T.},
  title     = {Investigation of the in-plane strain distribution in free-standing GaAs/InGaAs/GaAs single quantum well surface nanostructures on GaAs[001]},
  year      = {1999},
  language  = {en}
}
@article{EnglischBarberkaPietschetal.1995,
  author    = {Englisch, Uwe and Barberka, Thomas Andreas and Pietsch, Ullrich and H{\"o}hne, U.},
  title     = {Investigation of the chain-chain interface in a lead-stearate multilayer using neutron reflectivity},
  year      = {1995},
  language  = {en}
}
@article{ZeimerGrenzerPietschetal.2001,
  author    = {Zeimer, Ute and Grenzer, J{\"o}rg and Pietsch, Ullrich and Bugge, F. and Smirnitzki, V. and Weyers, Markus},
  title     = {Investigation of strain-modulated InGaAs-nanostructures by grazing-incidence x-ray diffraction and photoluminescence},
  year      = {2001},
  language  = {en}
}
@article{UlyanenkovKlemradtPietsch1998,
  author    = {Ulyanenkov, A. and Klemradt, U. and Pietsch, Ullrich},
  title     = {Investigation of strain relaxation in GaInAs/GaAs superlattices by x-ray diffuse scattering},
  year      = {1998},
  language  = {en}
}
@article{GeueSchultzEnglischetal.1999,
  author    = {Geue, Thomas and Schultz, M. and Englisch, Uwe and St{\"o}mmer, Ralph and Pietsch, Ullrich and Meine, Kerstin and Vollhard, D.},
  title     = {Investigation of pH-dependent domain structure of fatty acid salt Langmuir-Blodgett films by means of X-ray diffuse scattering and Atomic Force Microscopy},
  year      = {1999},
  language  = {en}
}
@article{KarcenkoEnglischGrenzeretal.2000,
  author    = {Karcenko, Anatolij V. and Englisch, Uwe and Grenzer, J{\"o}rg and Geue, Thomas and Pietsch, Ullrich and Siebrecht, R.},
  title     = {Investigation of partially deuterated multilayers by means of X-ray and polarized neutron reflectometry},
  issn      = {1044-8632},
  year      = {2000},
  language  = {en}
}
@article{EnglischKatholyPenacoradaetal.1999,
  author    = {Englisch, Uwe and Katholy, Stefan and Penacorada, Florencio and Reiche, J{\"u}rgen and Pietsch, Ullrich},
  title     = {Investigation of molecular diffusion across organic multilayers using neutron specular reflectivity},
  year      = {1999},
  language  = {en}
}