@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{PaschkeGeueBarberkaetal.1997, author = {Paschke, K. and Geue, Thomas and Barberka, Thomas Andreas and Bolm, A. and Pietsch, Ullrich and R{\"o}sch, M. and Batke, Edwin and Faller, F. and Kerkel, K. and Oshiniwo, J. and Forchel, Alfred}, title = {Characterization of lateral semiconductor nano structures by means of x-ray grazing-incidence diffraction}, year = {1997}, language = {en} } @article{ReicheKnochenhauerBarberkaetal.1995, author = {Reiche, J{\"u}rgen and Knochenhauer, Gerald and Barberka, Thomas Andreas and Geue, Thomas and Pietsch, Ullrich and Brehmer, Ludwig and Hodge, P. and Tredgold, Richard H.}, title = {In-plane structure of perfluorotetra decanoic acid Langmuir-Blodgett films and films formed by vacuum deposition}, year = {1995}, language = {en} } @article{StumpeGeueFischeretal.1995, author = {Stumpe, Joachim and Geue, Thomas and Fischer, Thomas M. and Menzel, Henning}, title = {Photochemically induced changes of structures in LB-multilayers of amphotropic polymers}, year = {1995}, language = {en} } @article{PietschBarberkaGeueetal.1997, author = {Pietsch, Ullrich and Barberka, Thomas Andreas and Geue, Thomas and St{\"o}mmer, Ralph}, title = {X-ray scattering from thin organic films and multilayers}, year = {1997}, language = {en} } @article{EichhornBruceGuillonetal.2001, author = {Eichhorn, Holger and Bruce, Duncan W. and Guillon, D. and Gallani, Jean Louis and Fischer, Thomas and Stumpe, Joachim and Geue, Thomas}, title = {Metal ion mediated mesomorphism and thin film behaviour of amphitropic tetraazaporphyrin complexes}, year = {2001}, language = {en} } @article{SchwarzSieversBodenthinetal.2010, author = {Schwarz, Guntram and Sievers, Torsten K. and Bodenthin, Yves and Hasslauer, Ires and Geue, Thomas and Koetz, Joachim and Kurth, Dirk G.}, title = {The structure of metallo-supramolecular polyelectrolytes in solution and on surfaces}, issn = {0959-9428}, doi = {10.1039/B926783b}, year = {2010}, abstract = {Metal ion induced self-assembly of the rigid ligand 1,4-bis(2,2':6',2 ''-terpyridine- 4'-yl) benzene (1) with Fe(II), Co(II), Ni(II) and Zn(II) acetate in aqueous solution results in extended, rigid- rod like metallosupramolecular coordination polyelectrolytes (MEPE-1). Under the current experimental conditions the molar masses range from 1000 g mol(-1) up to 500 000 g mol(-1). The molar mass depends on concentration, stoichiometry, metal-ion and time. In addition, we present viscosity measurements, small angle neutron scattering and AFM data. We introduce a protocol to precisely control the stoichiometry during self-assembly using conductometry. The protocol can be used with different terpyridine ligands and the above-mentioned metal ions and is of paramount importance to obtain meaningful and reproducible results. As a control experiment we studied the mononuclear 4'- (phenyl)2,2':6',2 ''-terpyridine (3) complex with Ni(II) and Zn(II) and the flexible ligand 1,3- bis[4'-oxa(2,2': 6',2 ''-terpyridinyl)] propane (2) with Ni(II) acetate (Ni-MEPE-2). This ligand does not form extended macroassemblies but likely ring-like structures with 3 to 4 repeat units. Through spin- coating of Ni-MEPE-1 on a solid surface we can image the MEPEs in real space by AFM. SANS measurements of Fe-MEPE-1 verify the extended rigid-rod type structure of the MEPEs in aqueous solution.}, language = {en} } @article{SchwarzBodenthinGeueetal.2010, author = {Schwarz, Guntram and Bodenthin, Yves and Geue, Thomas and Koetz, Joachim and Kurth, Dirk G.}, title = {Structure and properties of dynamic rigid rod-like metallo-supramolecular polyelectrolytes in solution}, issn = {0024-9297}, doi = {10.1021/Ma902057f}, year = {2010}, abstract = {Metal-ion-induced self-assembly in aqueous solution of the rigid ligand 1,4-bis(2,2':6',2 ''-terpyridine-4'-yl)benzene (1) with Fe(OAc)(2) and Ni(OAc)(2) is investigated with viscosimetry, SANS, and AFM. Ligand 1 forms extended, rigid-rod like metallo-supramolecular coordination polyeectrolytes (MEPEs) with a molar mass of up to 200 000 g mol(-1) under the Current experimental conditions. The molar mass depends oil concentration, stoichiometry, and time. By spin-coating MEPEs oil a solid surface, we call image the MEPEs in real space by AFM. Both AFM and SANS confirm the extended rigid-rod-type structure of the MEPEs. As a control experiment, we also studied the flexible ligand 1,3-bis[4'-oxa(2,2':6',2 ''-terpyridinyl)]propane (2). Ligand 2 does not form extended macro-assemblies but likely ringlike structures with three 10 four repeat units. Finally, we present it protocol to control the stoichiometry during self-assembly using conductometry, which is of paramount importance to obtain meaningful and reproducible results.}, 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{PietschBhattacharyaSanyaletal.2005, author = {Pietsch, Ullrich and Bhattacharya, M. K. and Sanyal, M. K. and Geue, Thomas}, title = {Glass transition in Ultrathin Polymer Films : a Thermal Expansion Study}, year = {2005}, abstract = {The glass transition process gets affected in ultrathin films having thickness comparable to the size of the molecules. We observe systematic broadening of the glass transition temperature (T-g) as the thickness of an ultrathin polymer film reduces below the radius of gyration but the change in the average T-g was found to be very small. The existence of reversible negative and positive thermal expansion below and above T-g increased the sensitivity of our thickness measurements performed using energy-dispersive x-ray reflectivity. A simple model of the T-g variation as a function of depth expected from sliding motion could explain the results}, language = {en} } @article{HennebergRochonPanzneretal.2004, author = {Henneberg, Oliver and Rochon, Paul and Panzner, Tobias and Finkelstein, Kenneth D. and Geue, Thomas and Saphiannikova, Marina and Pietsch, Ullrich}, title = {In-situ Investigation of Surface Relief Grating Formation in Photosensitive Polymers}, year = {2004}, 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{HennebergGeuePietschetal.2004, author = {Henneberg, Oliver and Geue, Thomas and Pietsch, Ullrich and Winter, Bernd}, title = {Investigation of azobenzene side group orientation in polymer surface relief gratings by means of photoelectron spectroscopy}, year = {2004}, abstract = {The molecular orientation of azobenzene side groups in polymer films before (nonpatterned) and after (patterned) development of a surface relief grating has been investigated by photoelectron spectroscopy using synchrotron radiation. The photoemission spectra obtained for 60-100 eV photons of a patterned and a nonpatterned surface are similar when the polarization vector of the synchrotron light is parallel to the grating vector. However, for perpendicular excitation, considerable spectral intensity differences can be observed for 9-14 eV electron binding energy. The observed changes are attributed to the formation of well-oriented azobenzenes at the surface. (C) 2004 American Institute of Physics}, language = {en} } @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{StillerKarageorgievBuchsteineretal.2003, author = {Stiller, Burkhard and Karageorgiev, Peter and Buchsteiner, Andrea and Geue, Thomas and Henneberg, Oliver and Brehmer, Ludwig and Natansohn, Almeria and Hollricher, Olga}, title = {Using light as a tool : optically Induced mass transport generated in Near-Fields}, issn = {0038-7355 -}, year = {2003}, language = {en} } @article{PietschPanznerLeitenbergeretal.2003, author = {Pietsch, Ullrich and Panzner, Tobias and Leitenberger, Wolfram and Grenzer, J{\"o}rg and Bodenthin, Th. and Geue, Thomas and M{\"o}hwald, Helmuth}, title = {Coherence experiments at the energy-dispersive reflectometry beamline at BESSY II}, year = {2003}, language = {en} } @article{PietschBhattacharyaMukherjeeetal.2003, author = {Pietsch, Ullrich and Bhattacharya, M. K. and Mukherjee, M. and Sanyal, M. K. and Geue, Thomas and Grenzer, J{\"o}rg}, title = {Energy dispersive x-ray reflectivity technique to study thermal properties of polymer films}, year = {2003}, language = {en} } @article{GeueHennebergGrenzeretal.2002, author = {Geue, Thomas and Henneberg, Oliver and Grenzer, J{\"o}rg and Pietsch, Ullrich and Natansohn, Almeria and Rochon, Paul and Finkelstein, Kenneth D.}, title = {Formation of a buried density grating on thermal erasure of azobenzene polymer surface gratings}, issn = {0927-7757}, year = {2002}, language = {en} } @article{GeueHennebergPietsch2002, author = {Geue, Thomas and Henneberg, Oliver and Pietsch, Ullrich}, title = {X-ray reflectivity from sinusoidal surface relief gratings}, issn = {0023-4753}, year = {2002}, language = {en} } @article{PietschKubowiczThuenemannetal.2003, author = {Pietsch, Ullrich and Kubowicz, Stephan and Th{\"u}nemann, Andreas F. and Geue, Thomas and Watson, M. D. and Tchebotareva, N. and M{\"u}llen, K.}, title = {X-ray reflectivity study of an amphiphilic hex-peri-hexabenzocoronene at a structured silicon wafer surface}, year = {2003}, language = {en} }