@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{ReichePenacoradaZetzscheetal.1995, author = {Reiche, J{\"u}rgen and Penacorada, Florencio and Zetzsche, Thomas and Katholy, Stefan and Brehmer, Ludwig}, title = {Polyelektrolyt-Fetts{\"a}ure-Multiphasen-LB-Schichten}, year = {1995}, language = {de} } @article{KnochenhauerReicheBarberkaetal.1995, author = {Knochenhauer, Gerald and Reiche, J{\"u}rgen and Barberka, Thomas Andreas and Woolley, Martin and Tredgold, Richard H. and Hodge, P. and Brehmer, Ludwig}, title = {Do perfluorianted chains always have to be twisted?}, year = {1995}, abstract = {Short perfluorinated cabon chains do not take on helical structure when they are closely packed}, language = {en} } @article{DietzelFreydankReicheetal.1995, author = {Dietzel, Birgit and Freydank, A. and Reiche, J{\"u}rgen and Brehmer, Ludwig and Knoblauch, H. and Knochenhauer, Gerald and Zetzsche, Thomas}, title = {Mono- und Multischichten von neuen aromatischen 1,3,4-Oxadiazolen}, year = {1995}, language = {de} } @article{PenacoradaDietelReicheetal.1995, author = {Penacorada, Florencio and Dietel, Reinhard and Reiche, J{\"u}rgen and Zetzsche, Thomas and Knobloch, Harald and Katholy, Stefan and Brehmer, Ludwig}, title = {Studium des Einflusses von Uranyl-Gegenionen auf die Struktur von Langmuir- und Langmuir-Blodgett Filmen der Arachins{\"a}ure}, year = {1995}, language = {de} } @article{HelmsReicheStilleretal.1995, author = {Helms, Andreas and Reiche, J{\"u}rgen and Stiller, Burkhard and Kobloch, H. and Brehmer, Ludwig}, title = {Herstellung d{\"u}nner organischer Schichten durch Vakuumdeposition}, year = {1995}, language = {de} } @article{ReicheBarberkaJanietzetal.1994, author = {Reiche, J{\"u}rgen and Barberka, Thomas Andreas and Janietz, Dietmar and Hofmann, Dieter and Pietsch, Ullrich and Brehmer, Ludwig}, title = {X-ray structure investigation and computer modelling of Langmuir-Blodgett films formed from disc-shaped pentaalkines}, year = {1994}, language = {en} } @article{AngelovaIonovReicheetal.1994, author = {Angelova, Angelina and Ionov, Radoslav and Reiche, J{\"u}rgen and Brehmer, Ludwig}, title = {Head-to tail or head-to-head structure of Langmuir-Blodgett long chain ester multilayers?}, year = {1994}, language = {en} } @article{ReicheKamusewitzKelleretal.1995, author = {Reiche, J{\"u}rgen and Kamusewitz, Helmut and Keller, Manuela and Brehmer, Ludwig and Pe{\~n}acorada, Florencio}, title = {Study of gas transport through composite membranes with a stabilised Langmuir-Blodgett skin layer}, year = {1995}, abstract = {The Langmuir-Blodgett (LB-) technique is used to deposit molecular reinforced separation layers on porous polymer substrates resulting in composite membranes for gas separation. The adsorption of a polycation to the arachidic acid Langmuir layer and the subsequent transfer of the highly ordered and stabilised monolayer onto a polypropylene membrane (Cellgard 2400) yields a laminated separation layer combining the advantageous high degree of order of fatty acid films and the stability of thin polymeric films. X-ray reflectivity data of these films confirm the transfer of the assembled polymer layer together with the fatty acid monolayer and the formation of ordered Y-type LB-films. SFM pictures show a dense film without pinholes completely covering the porous support. Gas permeation measurements are used to study the transport process of different gases through the composite membrane.}, language = {en} } @article{AngelovaReicheIonovetal.1994, author = {Angelova, Angelina and Reiche, J{\"u}rgen and Ionov, Radoslav and Janietz, Dietmar and Lemmetyinen, Helge and Brehmer, Ludwig}, title = {Control of the structure of Langmuir-Blodgett films of a discotic liquid crystalline compound via the subphase composition and the adjacent molecular environment}, year = {1994}, abstract = {Changes of the molecular arrangenemt that can be induced by means of the LB technique in the multilayers of a disc-shaped multialkynyl amphiphile are monitored by means of small angle X-ray diffraction. Studies of the monolayers at the air-water interface reveal "edge-on" orientation of the discs. Specific effects of the counter- ions (Na+, Cd²+, Pb²+, and Ba²+) and sub-solution pH on the monolayer collapse pressure, transfer efficiency and molecular order in the multilayers are found. A correlation between the monolayer properties and the ability for formation of periodic discotic structures in the presence of divalent counterions is established. The discotic molecules retain their "edge-on" arrangement in the highly compressed transferred films with slight irregular interdigtation of the flexible wings and inclination to the substrate normal. The tilt and the inter- digitation are reduced when the discotic monolayers are deposited in alternating LB films with barium arachidate spacer layers.}, 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{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{PenacoradaReicheZetzscheetal.1997, author = {Penacorada, Florencio and Reiche, J{\"u}rgen and Zetzsche, Thomas and Dietel, Reinhard and Brehmer, Ludwig and Saja, Jose-Antonio de}, title = {Stabilisation of fatty acid mono- and multilayers by simultaneous polyelectrolyte complexation and salt formation with cadmium ions}, year = {1997}, abstract = {The complexation of highly ordered fatty acid monolayers with polyelectrolytes is expected to yield well- ordered Langmuir films suitable for the formation of Langmuir-Blodgett multilayers with improved long-term stability. Studies of the surface pressure-area isotherms and of the surface potential kinetics yield detailed information regarding the influence of these polymeric counterions on the monolayer properties. The injection of bivalent metal salts into the subphase after the complexation was used to improve the order and stability of the mono- and multilayers. The corresponding Langmuir-Blodgett films were investigated by means of X-ray reflectivity measurements and scanning force microscopy. The polyion complex multilayers show a strongly increased mechanical stability compared with films of fatty acid salts formed with bivalent metal ions. These structures are expected to be suitable as ultrathin separation layer for gas separation or ultrafiltration membranes.}, language = {en} } @article{ReicheSchulzKnochenhaueretal.1997, author = {Reiche, J{\"u}rgen and Schulz, Burkhard and Knochenhauer, Gerald and Dietzel, Birgit and Freydank, Anke-Christine and Zetzsche, Thomas and Brehmer, Ludwig}, title = {Supramolecular structures formed from heterocyclic aromatic molecules}, year = {1997}, abstract = {This paper describes the formation and structure investigation of Langmuir monolayers and Langmuir-Blodgett multilayers formed from amphiphilic derivatives of 2,5-diphenyl-1,3,4-oxadiazole. The 2,5-diphenyl-1,3,4-oxadiazole group as a functional unit with interesting physical and chemical properties is maintained, while the head group, the length of the alkyl chain and the structure of the coupling unit between aromatic and aliphatic part of these linear short-chain amphiphiles is systematically varied in order to explore the influence of this change on the film forming properties and the stability of Langmuir and Langmuir-Blodgett films. Molecular mechanics simulations are shown by these systematic variations to be suitable for the prediction of optimal chemical structures allowing for a stable stratified molecular packing. The combination of a detailed structure investigation of the multilayers based on scanning force microscopy and X-ray data with molecular mechanics simulations yields an insight into the packing of the molecules and the intermolecular interactions.}, language = {en} } @article{PapraPenacoradaReicheetal.1997, author = {Papra, Alex and Penacorada, Florencio and Reiche, J{\"u}rgen and Katholy, Stefan and Brehmer, Ludwig and Hicke, Hans-Georg}, title = {Structure and Stability of Langmuir Monolayers and Langmuir-Blodgett Films of Bisaroyl Azide Bolaamphiphiles}, year = {1997}, abstract = {Langmuir-Blodgett films of bolaamphiphiles with reactive head groups can be used for the surface modification of composite membranes for gas separation processes. The scope of our investigations was to get a detailed insight in the monolayer behaviour and LB film structure of previously synthesized bisaroyl azide bolaamphiphiles. The layers have been analyses by means of surface potential measurements and Brewster angle microscopy. Furthermore parameters for a successful LB Film deposition were found. As expected for a molecule with two hydrophilic ends the transfer ratio on upstroke was close to one and on downstroke no transfer occurred. The multilayer structure was analysed by scanning force microscopy and X-ray reflectivity measurements. The SFM images revealed a periodic in plane structure on molecular level. Based on a combination of the X-ray data with results of other methods two possible models of the multilayer structure are presented}, language = {en} } @article{PenacoradaReicheDieteletal.1996, author = {Penacorada, Florencio and Reiche, J{\"u}rgen and Dietel, Reinhard and Zetzsche, Thomas and Stiller, Burkhard and Knobloch, Harald and Brehmer, Ludwig}, title = {Monolayers and multilayers of uranyl arachidate : 2. Influence of the subphase pH on the structure and stability of Langmuir-Blodgett films}, year = {1996}, abstract = {In this second paper we describe the comprehensive structure investigations on multilayers of uranyl arachidate formed by Langmuir-Blodgett deposition from subphases of different pH on solid substrates by means of a combination of infrared spectroscopy, X-ray specular reflection, ellipsometry, and scanning force microscopy, The structure of these multilayers and their stability are obviously influenced by the subphase pH. The pH range of the acid to salt conversion determined for the Langmuir films is confirmed by the infrared spectroscopic data of the multilayers. While arachidic acid films, deposited from an uranyl acetate subphase of low pH, are found to have strongly distorted rough surface, the films of uranyl structure, The influence of the counterions on the alkyl chain conformation, chain packing, reorganization probability, and stability of the multilayer is discussed.}, language = {en} } @article{ReicheBrehmer1995, author = {Reiche, J{\"u}rgen and Brehmer, Ludwig}, title = {Einfluss des Transferverh{\"a}ltnisses auf die Monoschichtsymmetrie in Y-Typ Langmuir-Blodgett-Schichten}, year = {1995}, language = {de} } @article{KatholyReicheBrehmer1995, author = {Katholy, Stefan and Reiche, J{\"u}rgen and Brehmer, Ludwig}, title = {Strukturuntersuchungen an Langmuir-Monoschichten organischer Amphiphile mittels Brewsterwinkelmikroskopie}, year = {1995}, language = {de} } @article{StillerKarageorgievPerezetal.2000, author = {Stiller, Burkhard and Karageorgiev, Peter and Perez, E. and Valez, M. and Reiche, J{\"u}rgen and Prescher, Dietrich and Dietzel, Birgit and Brehmer, Ludwig}, title = {Scanning kelvin microscopy as a tool for visualisation of optically induced molecular switching in azobenzene self assembling films}, issn = {0142-2421}, year = {2000}, language = {en} } @article{GieblerSchulzReicheetal.1999, author = {Giebler, Rainer and Schulz, Burkhard and Reiche, J{\"u}rgen and Brehmer, Ludwig and W{\"u}hn, Mario and W{\"o}ll, Christoph and Smith, Andrew Phillip and Urquhart, Steven G. and Ade, Harald W. and Unger, Wolfgang E. S.}, title = {Near-edge x-ray absorption fine structure spectroscopy on ordered films of an amphiphilic derivate of 2,5- Diphenyl-1,3,4-oxadiazole}, year = {1999}, abstract = {The surfaces of ordered films formed from an amphiphilic derivative of 2,5-diphenyl-1,3,4-oxadiazole by the Langmuir-Blodgett (LB) technique and organic molecular beam deposition (OMBD) were investigated by the use of near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. For the assignment of the spectral features of the C, N, and O K- edge absorption spectra, fingerprint spectra of poly(p-phenylene terephthalamide)(Kevlar), poly(ethylene terephthalate), poly(p-phenylene-1,3,4-oxadiazole), and 2,5-di- (pentadecyl)-1,3,4-oxadiazole, which contain related chemical moieties, were recorded. Ab initio molecular orbital calculations, performed with explicit treatment of the core hole, are used to support the spectral interpretations. Angle-resolved NEXAFS spectroscopy at the C, N, and O K-edges suggests a preferentially upright orientation of the oxadiazole derivative in the outermost layer of the films. X-ray specular reflectivity data and molecular modeling results suggest a similar interpretation.}, language = {en} } @article{ReicheFreydankHelmsetal.1999, author = {Reiche, J{\"u}rgen and Freydank, Anke-Christine and Helms, Andreas and Geue, Thomas and Schulz, Burkhard and Brehmer, Ludwig and Stiller, Burkhard and Knochenhauer, Gerald}, title = {Vacuum deposition films of oxadiazole compounds : formation and structure investigation}, year = {1999}, abstract = {The search for alternative routes of organic thin film formation is stimulated by the outstanding properties of these films in such fields as nonlinear optics, photonic data processing and molecular electronics. The formation of highly ordered multilayer structures by thermal vacuum deposition (VD) of organic compounds is an essential step toward the application of supramolecular organic architectures in technical systems. The VD of an amphiphilic substituted 2,5- diphenylene-1,3,4-oxadiazole 1 onto silicon substrates at defined temperature was used for the formation of ultrathin films. The structural data obtained for the VD-films of oxadiazole 1 by means of X-ray reflectivity, X-ray grazing incidence diffraction and atomic force microscopy (AFM) investigations indicate the formation of well ordered oxadiazole multilayers. The structure of the VD-multilayers is compared with that of Langmuir-Blodgett (LB) films and thermally treated LB-multilayers prepared from the same compound.}, language = {en} } @article{KnochenhauerPenacoradaReicheetal.1999, author = {Knochenhauer, Gerald and Penacorada, Florencio and Reiche, J{\"u}rgen and Brehmer, Ludwig and Tredgold, Richard H. and Barberka, Thomas Andreas}, title = {Multilayers of perfluorinated fatty acids}, year = {1999}, abstract = {We have formed Y layers of perfluorododecanoic acid CF3(CF2)10COOH by thermal evaporation in vacuo and of perfluorotetradecanoic acid CF3(CF2)12COOH by thermal evaporation and by the Langmuir-Blodgett (LB) technique. We have obtained the bilayer spacing of both these materials by X-ray diffraction and have also studied the in-plane structure of these materials by means of grazing incidence diffraction (GID). Computer modelling was used to interpret the results obtained. For the perfluorododecanoic acid, we find two stable untwisted phases at 25°C and a combination of these two predicts both the Bragg peaks arising from the layer structure and the GID results. Our experimental results show that the perfluorotetradecanoic acid exists in the generally accepted helical structure. Computer modelling leads to the conclusion that closely packed perfluorinated chains with 12 or less carbon atoms should exist in an untwisted state while molecules having more than 12 carbon atoms show the onset of the helical conformation.}, language = {en} } @article{SchraderVismantsDietzeletal.1999, author = {Schrader, Sigurd and Vismants, Z. and Dietzel, Birgit and Flueraru, C. and Prescher, Dietrich and Reiche, J{\"u}rgen and Motschmann, H. and Brehmer, Ludwig}, title = {Linear and nonlinear optical properties of Langmuir-Blodgett multilayers from chromophore-containing maleic acid anhydride polymers}, year = {1999}, language = {en} }