TY  - JOUR
A1  - Jarosz, Grazyna
A1  - Quinn, P. D.
A1  - Stephan, Niels
A1  - Brehmer, Ludwig
T1  - Dielectric properties of zinc phthalocyanine thin films : effects of annealing in air and in N-2
N2  - This work presents the effects of ambient conditions, in particular oxygen and humidity, on the dielectric spectra of thin zinc phthalocyanine (ZnPc) films equipped with interdigitated electrodes and the effect of annealing in dry N-2 or in ambient air. The measurements were performed in the frequency range 10(-2)-10(5) Hz. The results indicate that the electric properties of ZnPc films are not only affected by oxygen but also by water vapour the presence of which always leads to the drop in alternating current conductance (ac-conductance). Moreover, at room temperature, the ac-conductance of ZnPc films previously exposed to air exhibits a reversible change with humidity, which makes these films attractive for humidity sensing applications. (C) 2004 Elsevier B.V. All rights reserved
Y1  - 2005
SN  - 0040-6090
ER  - 
TY  - JOUR
A1  - Karageorgiev, Peter
A1  - Neher, Dieter
A1  - Schulz, Burkhard
A1  - Stiller, Burkhard
A1  - Pietsch, Ullrich
A1  - Giersig, Michael
A1  - Brehmer, Ludwig
T1  - From anisotropic photo-fluidity towards nanomanipulation in the optical near-field
N2  - An increase in random molecular vibrations of a solid owing to heating above the melting point leads to a decrease in its long-range order and a loss of structural symmetry. Therefore conventional liquids are isotropic media. Here we report on a light-induced isothermal transition of a polymer film from an isotropic solid to an anisotropic liquid state in which the degree of mechanical anisotropy can be controlled by light. Whereas during irradiation by circular polarized light the film behaves as an isotropic viscoelastic fluid, it shows considerable fluidity only in the direction parallel to the light field vector under linear polarized light. The fluidization phenomenon is related to photoinduced motion of azobenzene-functionalized molecular units, which can be effectively activated only when their transition dipole moments are oriented close to the direction of the light polarization. We also describe here how the photofluidization allows nanoscopic elements of matter to be precisely manipulated
Y1  - 2005
SN  - 1476-1122
ER  - 
TY  - JOUR
A1  - Penacorada, Florencio
A1  - Souto, Jorge
A1  - de Saja, J. A.
A1  - Brehmer, Ludwig
T1  - Brewster angle microscopy and surface potential measurements of Langmuir-Blodgett films of zinc tri(tert-butyl)- 4-sulphophthalocyanine
N2  - The formation of a Langmuir monolayer of an amphiphilic derivative of zinc phthalocyanine (Na[(ZnPcSO3)-S-t]) has been studied by means of surface potential technique and Brewster angle microscopy. The experiments were undertaken in order to understand the behaviour of this monolayer with a well-defined surface pressure isotherm. The floating film is described as a truly monomolecular layer formed by very rigid islands in which the phthalocyanine units tend to take on a preferential orientation with their planes perpendicular to the air-water interface, for high values of the surface pressure. (c) 2004 Elsevier B.V. All rights reserved
Y1  - 2005
SN  - 0169-4332
ER  - 
TY  - JOUR
A1  - Jarosz, Grazyna
A1  - Signerski, Ryszard
A1  - Brehmer, Ludwig
T1  - On dielectric spectra of thin copper phthalocyanine films
N2  - The work presents low signal dielectric spectra of gold/copper phthalocyanine/magnesium and gold/copper phthalocyanine/gold sandwich systems in the 25 Hz-1 MHz frequency range. The performed analysis enables us to distinguish the electrode resistance and the lattice polarization from processes related with electric transport, such as charge carrier relaxation at space charge region of a barrier and charge carrier injection in dielectric response.
Y1  - 2006
UR  - http://www.sciencedirect.com/science/journal/00406090
U6  - https://doi.org/10.1016/j.tsf.2006.02.035
SN  - 0040-6090
ER  - 
TY  - BOOK
A1  - Muzikante, I.
A1  - Fonavs, E.
A1  - Brehmer, Ludwig
A1  - Stiller, Burkhard
T1  - Photoinuced phenomena in corona poled polar organic films
N2  - Organic materials have received considerable attention because of their large dipole moments and optical nonlinearities. The optically induced switching of material properties is important for studying the optoelectronic effects including second harmonic generation. Organic materials for photonic applications contain chromophore dipole which consist of acceptor and donor groups bridged by a delocalized pi-electron system. Both theoretical and experimental data show a reversible highly dipolar photoinduced intra molecular charge transfer in betaine type molecules accompanied by change of the sign and the value of the dipole moment. The arrangement of polar molecules in films is studied both by atom force microscopy and surface potential measurements. To understand the photo response of these materials, their spectroscopic and electrical properties are studied. The morphology and photoinduced surface potential switching of the self-assembled monolayers and polymer films are investigated. (c) 2005 Elsevier B.V. All rights reserved
Y1  - 2005
ER  - 
TY  - BOOK
A1  - Smertenko, P.
A1  - Fenenko, L.
A1  - Brehmer, Ludwig
A1  - Schrader, Sigurd
T1  - Differential approach to the study of integral characteristics in polymer films
N2  - The differential approach is based on the determination of dimensionless differential slope, for instance, of current-voltage characteristics (IVC), I=f(V). This slope (a) is given by formula alpha=d(lgI)/d(lgV). With such definition the ranges of constancy of the a(V) dependency correspond to the part of IVC characterized by the power behaviour (I similar to V-alpha). The differential slope of alpha(V) dependency gamma = d(lg alpha)/dlgV determines the exponent behaviour of curve (I similar to exp {eV(y)/kT}). Processing by the differential approach of the investigated theoretical or experimental characteristics permits us to determine the peculiarity of charge flow mechanisms, temperature behaviour of conductivity, etc. The theoretical base and some applications of differential approach to the investigation of the current-voltage, temperature and degradation characteristics of the polyaniline and poly(p- phenilenevinilene) based structures have been shown. (c) 2005 Elsevier B.V. All rights reserved
Y1  - 2005
ER  - 
TY  - JOUR
A1  - Dimitriev, O. P.
A1  - Smertenko, P. S.
A1  - Stiller, Burkhard
A1  - Brehmer, Ludwig
T1  - Polyaniline-transition metal salt complexes: insight into formation mechanisms
N2  - Two basic morphologies of emeraldine base of polyaniline-transition metal salt complex films cast from N- methylpyrrolidinone solutions are described. The first morphology consists of grains and the other consists of loose aggregates, respectively. The correlation of the film morphology with formation of precipitate in the complex solution, kinetics of solvent evaporation from the cast film, amount of solvent entrapped in the film, film conductivity, and IR absorption spectra is shown. Two different mechanisms of the complex formation as a result of competition in the polymer- inorganic salt-solvent trio interactions are discussed; the first mechanism results in folding of macromolecules into compact coils being then a core of grains in the complex films, and the second mechanism leads to blending of the polymer chains with solvent giving rise to formation of loose aggregates. (c) 2005 Elsevier B.V. All rights reserved
Y1  - 2005
SN  - 0379-6779
ER  - 
TY  - JOUR
A1  - Muzikante, I.
A1  - Fonavs, E.
A1  - Tokmakov, A.
A1  - Cepite, D.
A1  - Stiller, Burkhard
A1  - Brehmer, Ludwig
A1  - Neilands, O.
T1  - Optical and electrical properties of oriented thin films of oligomer containing betaine-type moiety in side chain
N2  - Non-linear optical and electrical properties of polymer films obtained by dipole orientation of active units are reported. Novel polar oligomer with N-(indan-1,3-dion-2-yl)pyridinium betaine (IPB) as a side group is studied. Orientation of polar groups in oligomer thin films causes an increase of the photo-induced change of surface potential on irradiation in the region of photo-induced electron transfer (PIET) where the IPB group exhibits a reversible change of the value and sign of the dipole moment. At longer wavelengths, the value of the surface potential of the oligomer may be determined by transport of photo-generated charge carriers
Y1  - 2005
SN  - 0370-1972
ER  - 
TY  - JOUR
A1  - Wong, J. E.
A1  - Detert, H.
A1  - Brehmer, Ludwig
A1  - Schrader, Sigurd
T1  - Green light-emitting devices based on soluble oligo(phenylenevinylenes)
N2  - In this work, we report our investigations on the film-forming properties as well as the optical and electroluminescent characterisations of a series of lateral-substituted soluble oligo(phenylenevinylenes) of various conjugation length. Preliminary investigations show that these materials are potential candidates for use in organic light-emitting devices (OLEDs). Two types of OLEDs were fabricated: single layer (SL) and single heterostructure (SHS), with poly(p-phenylenevinylene) (PPV) as hole transporting layer. Our best results were obtained with single layer device emitting green light with a luminance of 0.18 cd m(-2) and 0.24 cd m(-2) at a driving voltage of 10 V. (c) 2004 Elsevier B.V. All rights reserved
Y1  - 2005
SN  - 0169-4332
ER  - 
TY  - JOUR
A1  - Bochenkov, V.
A1  - Karageorgiev, Peter
A1  - Brehmer, Ludwig
A1  - Sergeev, G. B.
T1  - Quenched growth of nanostructured lead thin films on insulating substrates
N2  - Lead island films were obtained via vacuum vapor deposition on glass and ceramic substrates at 80 K. Electrical conductance was measured during vapor condensation and further annealing of the film up to room temperature. The resistance behavior during film formation and atomic force microscopy of annealed films were used as information sources about their structure. A model for the quenched growth, based on ballistic aggregation theory, was proposed. The nanostructure, responsible for chemiresistive properties of thin lead films and the mechanism of sensor response are discussed. (C) 2003 Elsevier B.V. All rights reserved
Y1  - 2004
SN  - 0040-6090
ER  - 
TY  - JOUR
A1  - Wang, G.
A1  - Nespurek, S.
A1  - Rakusan, J.
A1  - Karaskova, M.
A1  - Schauer, F.
A1  - Brehmer, Ludwig
T1  - Polarized electrolumineseence from bilayer structures
N2  - The photoalignment ability of poly[methyl(phenyl)silylene] (PMPSi) films makes it possible to use them as hole- transporting substrates for the preparation of organic oriented films. A PMPSi layer prepared by spin coating was irradiated, after drying, with linearly polarized UV light. Then, water-soluble hydroxyaluminium phthalocyaninesulfonate [Al(OH)Pc(SO3Na)(1-2)] was deposited by casting. The cell ITO/PMPSi/AI(OH)Pc(SO3Na)(1-2)/Al showed non-linear current- voltage characteristics. For applied voltages higher than 10 V, polarized electroluminescence was observed. Its spectral characteristic consisted of two peaks with maxima at about 320 and 700 nm; their polarized anisotropies R-EL = Phi(parallel to) / Phi(perpendicular to) were ca. 15 and 0.5, respectively
Y1  - 2004
SN  - 1022-1360
ER  - 
TY  - JOUR
A1  - Smertenko, P. S.
A1  - Dimitriev, O. P.
A1  - Schrader, Sigurd
A1  - Brehmer, Ludwig
T1  - Doping of polyaniline by transition metal salts : current-voltage characteristics of the ITO/polymer film/metal heterostructures
N2  - Films of emeraldine base of polyaniline (PAni) doped by various transition metal salts have been prepared, and current-voltage characteristics of the indium-tin oxide (ITO)/PAni film/metal electrode heterostructures were investigated. It was found that the electrical characteristics of the heterostructures are greatly affected by the dopant used and the metal electrode used. Different dopants resulted in different current anomalies with asymmetric current-voltage characteristics. Depending on the dopant used, the exponential and power law of the current behavior can be distinguished. Depending on the metal electrode used, two different regimes of current passing have been found at low applied voltages, namely, a nearly ohmic regime for the indium electrode, and a diode regime for the aluminum electrode. The diode regime was found to accompany by a positive charge accumulation in the film near the film/metal interface, which creates a built-in potential in the film. The amount of positive charges accumulated at the interface and therefore the value of the built-in potential can be reversibly increased or reduced by successive runs of the applied voltage in the forward or reverse direction, respectively. (C) 2004 Elsevier B.V. All rights reserved
Y1  - 2004
SN  - 0379-6779
ER  - 
TY  - JOUR
A1  - Stiller, Burkhard
A1  - Karageorgiev, Peter
A1  - Buchsteiner, Andrea
A1  - Geue, Thomas
A1  - Henneberg, Oliver
A1  - Brehmer, Ludwig
A1  - Natansohn, Almeria
A1  - Hollricher, Olga
T1  - Using light as a tool : optically Induced mass transport generated in Near-Fields
Y1  - 2003
SN  - 0038-7355 -
ER  - 
TY  - BOOK
A1  - Brehmer, Ludwig
T1  - Gründung und Gründer der Hochschul-Physik in Potsdam Sanssouci
BT  - die schweren Anfangsjahre 1948-1958, Gründung und Gründer, Aufbau und Entwicklung, Eingliederung in die neu errichtete Universität (2022)
T3  - Die Hochschulstadt in Potsdam-Sanssouci ; Band 9
Y1  - 2022
SN  - 978-3-9821787-6-9
PB  - Eigenverlag
CY  - Potsdam
ER  - 
TY  - BOOK
A1  - Brehmer, Ludwig
T1  - 70-jähriges-Jubiläum der Gründung der Hochschul-Biologie und des Botanischen Gartens der Pädagogischen Hochschule Potsdam
BT  - eine administrative und wissenschafts-politische Retrospektive und Würdigung der Gründer
T3  - Die Hochschulstadt in Sanssouci ; Band 8
Y1  - 2020
SN  - 978-3-9821787-3-8
PB  - Eigenverlag des Verfassers Brehmer
CY  - Schwielowsee
ER  - 
TY  - JOUR
A1  - Brehmer, Ludwig
T1  - Supramolecular architectures for micro-sensorics and molecular electronics
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Brehmer, Ludwig
T1  - WEH Ferienkurs "Komplexe organisierte Grenz- und Oberfläche"
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Höpfner, Ulf
A1  - Frübing, Peter
A1  - Neumann, Werner
A1  - Kaminorz, Yvette
A1  - Brehmer, Ludwig
T1  - Polarization Processes of poly(DMDAAC) films studied by TSD current
Y1  - 1996
ER  - 
TY  - JOUR
A1  - Knobloch, Harald
A1  - Katholy, Stefan
A1  - Orendi, H.
A1  - Hesse, J.
A1  - Ruhmann, Ralf
A1  - Prescher, Dietrich
A1  - Brehmer, Ludwig
T1  - Ellipsometric studies on photochromic ultra thin polymer films
Y1  - 1996
ER  - 
TY  - JOUR
A1  - Brehmer, Ludwig
A1  - Kaminorz, Yvette
A1  - Grasnick, G.
A1  - Herkner, G.
T1  - Organic thin film pyrosensors
Y1  - 1996
ER  - 
TY  - JOUR
A1  - Knobloch, Harald
A1  - Szada-Borryszkowski, Gunther v.
A1  - Woigk, S.
A1  - Helms, Andreas
A1  - Brehmer, Ludwig
T1  - Dispersive surface plasmon microscopy for the characterization of ultra thin organic films
Y1  - 1996
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Dietel, Reinhard
A1  - Lemmetyinen, Helge
A1  - Janietz, Dietmar
A1  - Lemmetyinen, Helge
A1  - Brehmer, Ludwig
T1  - Edge-on Langmuir-Blodgett multilayers derived from disc-shaped multiyne mesogens
N2  - Langmuir-Blodgett(LB) multilayers were prepared from disc-shaped multiyne mesogens based on amphiphilic alkyl pentakis(aryl-ethynyl)benzene ethers. The two compounds used are characterized by five hydrophobic flexible chains and one hydrophilic substituent at the terminal position of the alkoxy chain. The LB films were analysed by X-ray scattering and spectroscopic measurements. An edge-on arrangement of the two discotic pentaalkynes within Y-type bilayers with a different packing density proved to be possible for the LB films of both compounds.
Y1  - 1992
ER  - 
TY  - JOUR
A1  - Zhu, Shigen
A1  - Schulz, Burkhard
A1  - Bruma, Maria
A1  - Brehmer, Ludwig
T1  - Comparative study of the thermal properties of related aromatic polyhydrazides and poly(1,3,4-oxadiazole)s
Y1  - 1996
UR  - http://www3.interscience.wiley.com/journal/5401/home?CRETRY=1&SRETRY=0
U6  - https://doi.org/10.1002/(SICI)1099-1581(199612)7:12<879::AID-PAT600>3.0.CO;2-X
SN  - 1042-7147
ER  - 
TY  - JOUR
A1  - Albrecht, Fred
A1  - Brehmer, Ludwig
A1  - Liemant, Alfred
T1  - Hopping transport in a disordered lattice simulation of dark discharge
N2  - On the basis of a stochastic model of hopping transport in disordered solids we present results of simulations of the dark discharge of surface charged thin films considering the energetic distribution of the localised states within the sheet. A non- linear differential equation with suitable boundary and initial conditions describes the time evolution of the space charge. We suppose a Gaussian distribution of energies for the carrier transporting states with a standard deviation s. The arrival time of carriers at the rear electrode of the sandwich sample is studied in dependence on film thickness, initial surface charge, and energetic disorder. Our calculations confirm that the transit time increases indirect proportional with initial surface charge and proportional with the square thickness. For standard deviations of energetic distribution of 0.05 eV up to 0.25 eV the normalised transit time grows as s1.44. We discuss this in terms of the stochastic transport model.
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Janietz, Dietmar
A1  - Katholy, Stefan
A1  - Brehmer, Ludwig
T1  - Monolayer properties of Amphiphilic Tetrakis(phenylethynyl)benzene compounds
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Schulz, Burkhard
A1  - Stiller, Burkhard
A1  - Zetzsche, Thomas
A1  - Knochenhauer, Gerald
A1  - Brehmer, Ludwig
T1  - Characterization of crystals based on 1,3,4-oxadiazoles by atomic force microscopy
N2  - The surface structures of crystals based on aromatic oxadiazoles were investigated by AFM. The crystal structure for 2,5-di(p-tolyl)-1,3,4-oxadiazole (DTO) differs from that of 2,5-di (4-methoxycarbonyl-phenyl)-1,3,4- oxadiazole (DMPO). In DMPO all molecules show parallel orientation to the surface in such a way that the surface is formed as well as by the nitrogen atoms of the heterocyclic rings and the methyl groups of the ester substituents. By contrast, the oxadiazole molecules in DTO crystals are oriented perpendicular to the crystal surface. The experimental data are interpreted by molecular modelling. It is shown that there is a difference between molecular structure of the surface, as detected by AFM, and the bulk structure determined by X-ray diffraction.
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Zetzsche, Thomas
A1  - Helms, Andreas
A1  - Freydank, Anke-Christine
A1  - Knochenhauer, Gerald
A1  - Schulz, Burkhard
A1  - Brehmer, Ludwig
T1  - Organized molecular films of oxadiazole compounds formed by vacuum deposition
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Schröter, J. A.
A1  - Plehner, R.
A1  - Tschierske, C.
A1  - Katholy, Stefan
A1  - Janietz, Dietmar
A1  - Peñacorada, Florencio
A1  - Brehmer, Ludwig
T1  - Monolayer properties of a new family of amphiphiles with an unusual head-group topology
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Janietz, Dietmar
A1  - Katholy, Stefan
A1  - Dietzel, Birgit
A1  - Brehmer, Ludwig
T1  - Monolayer behaviour of two-fold hydroxy terminated sheet-like Tetrakis(phenylethynyl) benzene derivatives
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Knobloch, Harald
A1  - Peñacorada, Florencio
A1  - Brehmer, Ludwig
T1  - Ellipsometric studies on Uranyl Arachidate Langmuir-Blodgett films
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Penacorada, Florencio
A1  - Angelova, Angelina
A1  - Kamusewitz, Helmut
A1  - Reiche, Jürgen
A1  - Brehmer, Ludwig
T1  - Scanning Force Microscopy and Wetting study of the Surface Modification of a Polypropylene Mambrane by Means of Langmuir-Blodgett Film Deposition
N2  - Polypropylene membranes with deposited ultrathin "siin" layers are attractive for separation and cleaning of gaseous mixtures. In the present study, the surface morphology and wetting hysteresis of composite membranes consisting of a microporous polypropylene support and Langmuir-Blodgett ("skin") films, are investigated. The effect of the interlayer molecular interactions and the substrate features on the integrity and homogeneity of the "skin" layers is examined. Langmuir-Blodgett films of arachidic acid and cadmium and calcium arachidate are characterized both on smooth silicon and on porous polypropylene supports. Contact angle measurements and scanning force microscopy (SFM) are applied for investigations of the membrane surface modification upon transfer of a different number of monolayers. It was found that the contact angle hysteresis of the bare membrane decreases after the LB-deposition of close-packed monolayers. Smoothing of the membrane surface is also evidenced by the SFM images, on different length scales, confirming a good coverage of the membrane pores.
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Janietz, Dietmar
A1  - Barberka, Thomas Andreas
A1  - Hofmann, Dieter
A1  - Brehmer, Ludwig
T1  - Comprehensive structure investigation of Langmuir-Blodgett films of disc-shaped molecules
N2  - The structure of mono- and multilayers of amphiphilic disc-shaped pentaynes wa inbestigated by Brewsterangle microscopy, X-ray specular reflection and grazing incidence diffraction (GID). X-ray specular reflection experiments confirm the "edge on" arrangement of the molecular discs. The molecular modelling of the Langmuir-Blodgett (LB)- multilayers predicts a columnar in-plane packing of the molecules. A GID experiment with monochromatic synchrotron radiation was used to verify the predicted multilayer structure on molecular level, while the Brewsterangle microscopy gave a deeper insight in the monolayer in-plane structure on micron scale.
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Penacorada, Florencio
A1  - Reiche, Jürgen
A1  - Katholy, Stefan
A1  - Brehmer, Ludwig
A1  - Rodriguez-Mendez, Maria-Luisa
T1  - Monolayers and multilayers of uranyl arachidate : 1. study of the interaction of dissolved uranyl ions with arachidic acid Langmuir monolayers
N2  - Langmuir monolayers of arachidic acid have been prepared on a subphase containing uranyl ions (O-U-O)ý+. The interaction between the uranyl ions and the monolayer of arachidic acid has been studied by means of surface pressure and surface potential isotherms and Brewster angle microscopy at different pH values (ranging from 1.5 to 8). A similar systematic study has been carried out in the presence of Cdý+ ions for comparison purposes. The surface pressure and surface potential isotherms demonstrate that the acid to salt conversion of arachidic acid in the presence of uranyl ions occurs at lower bulk pH values (pH=3.5) as compared with other bivalent metal counterions such as Cdý+. Changes in the surface morphology of the monolayer induced by the interaction with uranyl- and cadmium ions are analyzed and the correlation between the surface potential change and the morphology of the films is discussed.
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Freydank, A.
A1  - Dietzel, Birgit
A1  - Katholy, Stefan
A1  - Knochenhauer, Gerald
A1  - Zetzsche, Thomas
A1  - Schulz, Burkhard
A1  - Brehmer, Ludwig
T1  - Komplexe Strukturanalytik von Oxadiazol-Mono- und Multischichten
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Penacorada, Florencio
A1  - Geue, Thomas
A1  - Pietsch, Ullrich
A1  - Brehmer, Ludwig
T1  - In-plane structure of uranylarachidate multilayers
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Brehmer, Ludwig
A1  - Dietzel, Birgit
A1  - Freydank, Anke-Christine
A1  - Katholy, Stefan
A1  - Knochenhauer, Gerald
A1  - Reiche, Jürgen
A1  - Schulz, Burkhard
A1  - Zetzsche, Thomas
T1  - Langmuir- und Langmuir-Blodgett-Filme amphiphiler Oxadiazole
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Schulz, Burkhard
A1  - Bruma, Maria
A1  - Brehmer, Ludwig
T1  - Aromatic poly(1,3,4-oxadiazole)s as advanced materials
N2  - Poly(1,3,4-oxadiazole)s have been the focus of considerable interest with regard to the- production of high- performance materials, particularly owing to their high thermal stability in oxidative atmosphere and specific properties determined by the structure of 1,3,4-oxadiazole ring, which, from the spectral and electronic points of view, is similar to a p-phenylene structure.[1] Besides their excellent resistance to high temperature, polyoxadiazoles have many desirable characteristics, such as good hydrolytic stability, high glass transition temperatures, low dielectric constants, and tough mechanical properties. Some polyoxadiazoles have semiconductive properties, other structures can be electrochemically doped and thus made conductive, and other have liquid-crystalline properties, which make them very attractive for a wide range of high-performance applications. They exhibit excellent fiber- and film-forming capabilities, thus being considered for use as heat-resistant reinforcing fibers for advanced composite materials, highly resistant fabrics for the filtration of hot gases, special membranes for gas separation or reverse osmosis, precursors for highly oriented graphite fibers, films, and blocks to be used in the construction of electronic instruments based on X-rays, neutron beams, or a-particles, or in the construction of nuclear reactor walls. Since they were first reported in 1961,[2] a wide variety of polymers containing 1,3,4-oxadiazole rings have been synthesized, and their preparation, characterization, and physico-mechanical properties have been periodically reviewed .[3-8] This article will present a general overview of this class of polymers and will refer to the work carried out by different researchers in the last ten years with the emphasis on the potential uses of such polymers as advanced materials.
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Schulz, Burkhard
A1  - Kaminorz, Yvette
A1  - Brehmer, Ludwig
T1  - New aromatic poly(1,3,4-oxadiazole)s for light emitting diodes
N2  - New aromatic poly(1,3,4-oxadiazole)s were synthesized having excellent film forming properties due to their solubility in common organic solvents. The investigated new polyoxadiazoles can be used as emission material in single layer LED. The poly- oxadiazoles show an emission in the range of blue to yellow light. The external quantum efficiency as well as the turn-on voltage of the devices are influenced when blends of the polyoxadiazole with hole transport materials are used.
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Liemant, Alfred
A1  - Brehmer, Ludwig
T1  - A mean field approximation for hopping transport in disordered materials
Y1  - 1996
ER  - 
TY  - JOUR
A1  - Brehmer, Ludwig
T1  - Ellipsometrie an photochromen ultradünnen Polymerschichten
Y1  - 1996
ER  - 
TY  - BOOK
A1  - Brehmer, Ludwig
T1  - Die Brandeburgische Landeshochschule zu Potsdam im Jahre eins : die Hochschule in Potsdamer Schulen ; Daten und Fakten ; Kommentare und Dokumente
Y1  - 2011
SN  - 978-3-00-034135-9
VL  - 4
PB  - Eigenverl. des Verf
CY  - Potsdam
ER  - 
TY  - JOUR
A1  - Geue, Thomas
A1  - Katholy, Stefan
A1  - Reiche, Jürgen
A1  - Brehmer, Ludwig
A1  - Caliebe, W.
T1  - Grazing incidence x-ray diffraction (GIXD) measurements of uranyl arachidate (UO2A2) LB films
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Knochenhauer, Gerald
A1  - Barberka, Thomas Andreas
A1  - Geue, Thomas
A1  - Pietsch, Ullrich
A1  - Brehmer, Ludwig
A1  - Hodge, P.
A1  - Tredgold, Richard H.
T1  - In-plane structure of perfluorotetra decanoic acid Langmuir-Blodgett films and films formed by vacuum deposition
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Dietzel, Birgit
A1  - Freydank, Anke-Christine
A1  - Geue, Thomas
A1  - Pietsch, Ullrich
A1  - Brehmer, Ludwig
T1  - Lateral structure of thermally treated oxadiazole Langmuir-Blodgett films
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Penacorada, Florencio
A1  - Zetzsche, Thomas
A1  - Katholy, Stefan
A1  - Brehmer, Ludwig
T1  - Polyelektrolyt-Fettsäure-Multiphasen-LB-Schichten
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Schulz, Burkhard
A1  - Brehmer, Ludwig
A1  - Dietzel, Birgit
A1  - Zetzsche, Thomas
T1  - Preparation and characterization of ordered thin films based on aromatic poly(1,3,4-oxadiazole)s
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Schulz, Burkhard
A1  - Knochenhauer, Gerald
A1  - Brehmer, Ludwig
A1  - Janietz, Silvia
T1  - Stuctures and properties of aromatic poly(1,3,4-oxadiazole)s
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Yusupov, R. G.
A1  - Frübing, Peter
A1  - Brehmer, Ludwig
A1  - Mislavski, B. V.
T1  - Langmuir Filme des Polymers "NAFION" als sensibles Element eines Feuchtesensors
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Schulz, Burkhard
A1  - Stiller, Burkhard
A1  - Zetzsche, Thomas
A1  - Knochenhauer, Gerald
A1  - Dietel, Reinhard
A1  - Brehmer, Ludwig
T1  - Characterization of 2,5-di(p-tolyl-1,3,4- oxadiazole) crystals by IR-spectroscopy and atomic force microscopy
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Brehmer, Ludwig
A1  - Grasnick, G.
A1  - Herkner, G.
A1  - Kaminorz, Yvette
T1  - Organic thin film pyrosensors
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Brehmer, Ludwig
A1  - Frübing, Peter
A1  - Herkner, G.
A1  - Kaminorz, Yvette
T1  - Pyroelektrische Untersuchungen an dünnen Schichten von organischen Seitenkettenpolymeren
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Brehmer, Ludwig
A1  - Liemant, Alfred
A1  - Müller, I.
A1  - Albrecht, Fred
T1  - Stochastic model for charge carrier transport in disordered solids
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Knobloch, Harald
A1  - Woigk, S.
A1  - Brehmer, Ludwig
A1  - Yusupov, R. G.
A1  - Rakhnyanskaya, A.
T1  - Metalion adsorption to Langmuir-Blodgett films monitored by the optical waveguide technique
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Penacorada, Florencio
A1  - Yusupov, R. G.
A1  - Milaski, B.
A1  - Frübing, Peter
A1  - Brehmer, Ludwig
T1  - Elektrische Eigenschaften von polyionischen LB-Filmen
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Kaminorz, Yvette
A1  - Smela, E.
A1  - Inganäs, O.
A1  - Brehmer, Ludwig
T1  - Sensitivity of polythiophene planar light emitting diodes to oxygen
N2  - Surface light emitting diodes (SLEDs) with a polymer-on-top geometry were used to study the sensitivity of light emission to oxygen. In these devices, pre-fabricated electrodes were coated with a conjugated polymer, which was thus directly exposed to the environment. Oxygen caused an immediate ten-to hundred fold decrease in electroluminescence efficiency relative to that in nitrogen or argon. Above the voltage for light emission, there was a sharp increase in current. Removing the oxygen led to recovery of the light intensity over a period of minutes, but the current returned immediately to its lower, original level. The electroluminescence and photoluminescence spectra were identical and were unaltered in shape by oxygen exposure (only decreasing in size). However, photoluminescence was unaffected by oxygen alone. This result indicates that oxygen does not affect excitons directly, but rather influences an intermediate species on the path to exciton formation, one that is significant only in electroluminescence and not in photoluminescence. Under simultaneous exposure to oxygen and UV light, the photoluminescence irreversibly decreased, presumably due to photo-oxidation
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Smela, E.
A1  - Kaminorz, Yvette
A1  - Inganäs, O.
A1  - Brehmer, Ludwig
T1  - Planar microfabricated polymer light-emitting diodes
N2  - Conjugated polymers are organic semiconducting materials that can emit light. These polymers have the advantages of being light, cheap, and easy to process, and in addition the band gap can be tailored. We report the microfabrication of surface light emitting diodes (SLEDs) on silicon substrates in which the electrodes are underneath the organic electroluminescent layer. Patterned electrodes are separated by a 2500Å-thick insulating layer of silicon oxide or are interdigitated with a separation of 10 or 20 µm; the luminescent polymer is spin-coated or solvent cast on top of the electrodes. This fabrication method is completely compatible with conventional silicon processing because the polymer is deposited last and the light is emitted from the upper surface of the diodes. Despite the large spacing between electrodes, and despite the absence of an evaporated top contact, the voltages required for light emission were not much greater than those used in conventional sandwich-type structures
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Knochenhauer, Gerald
A1  - Reiche, Jürgen
A1  - Barberka, Thomas Andreas
A1  - Woolley, Martin
A1  - Tredgold, Richard H.
A1  - Hodge, P.
A1  - Brehmer, Ludwig
T1  - Do perfluorianted chains always have to be twisted?
N2  - Short perfluorinated cabon chains do not take on helical structure when they are closely packed
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Dietzel, Birgit
A1  - Freydank, A.
A1  - Reiche, Jürgen
A1  - Brehmer, Ludwig
A1  - Knoblauch, H.
A1  - Knochenhauer, Gerald
A1  - Zetzsche, Thomas
T1  - Mono- und Multischichten von neuen aromatischen 1,3,4-Oxadiazolen
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Bauer, J.
A1  - Schulz, Burkhard
A1  - Brehmer, Ludwig
A1  - Bötcher, M.
A1  - Jagdhold, U.
A1  - Höppner, K.
A1  - Kulesch, A.
A1  - Dietzel, Birgit
T1  - Anwendung von Langmuir-Blodgett-Schichten als Resist für die Niederspannungs-Elektronenstrahl-Lithografie
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Penacorada, Florencio
A1  - Dietel, Reinhard
A1  - Reiche, Jürgen
A1  - Zetzsche, Thomas
A1  - Knobloch, Harald
A1  - Katholy, Stefan
A1  - Brehmer, Ludwig
T1  - Studium des Einflusses von Uranyl-Gegenionen auf die Struktur von Langmuir- und Langmuir-Blodgett Filmen der Arachinsäure
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Frübing, Peter
A1  - Grasnick, G.
A1  - Herkner, G.
A1  - Janietz, Dietmar
A1  - Brehmer, Ludwig
T1  - Pyroelektrische Untersuchungen an Polyvinylalkoholen mit Azobenzen / Alkoxy - Seitenketten
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Helms, Andreas
A1  - Reiche, Jürgen
A1  - Stiller, Burkhard
A1  - Kobloch, H.
A1  - Brehmer, Ludwig
T1  - Herstellung dünner organischer Schichten durch Vakuumdeposition
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Metzger, Robert M.
A1  - Chen, Bo
A1  - Höpfner, Ulf
A1  - Lakshmikantham, M. V.
A1  - Vuillaume, Dominique
A1  - Kawai, Tsuyoshi
A1  - Wu, Xiangli
A1  - Tachibana, Hiroaki
A1  - Hughes, Terry
A1  - Sakurai, Hiromi
A1  - Baldwin, Jeffrey W.
A1  - Hosch, Christina
A1  - Cava, Michael P.
A1  - Brehmer, Ludwig
A1  - Ashwell, Geoffrey J.
T1  - Unimolecular electrical rectification in Hexadecylquinolinium Tricyanoquinodimethanide
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Dietel, Reinhard
A1  - Penacorada, Florencio
A1  - Brehmer, Ludwig
T1  - Structural variations in Langmuir-Blodgett layers of arachidic acid studied by FTIR-reflection absorption spectroscopy
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Barberka, Thomas Andreas
A1  - Janietz, Dietmar
A1  - Hofmann, Dieter
A1  - Pietsch, Ullrich
A1  - Brehmer, Ludwig
T1  - X-ray structure investigation and computer modelling of Langmuir-Blodgett films formed from disc-shaped pentaalkines
Y1  - 1994
ER  - 
TY  - JOUR
A1  - Angelova, Angelina
A1  - Penacorada, Florencio
A1  - Stiller, Burkhard
A1  - Zetzsche, Thomas
A1  - Ionov, Radoslav
A1  - Kamusewitz, Helmut
A1  - Brehmer, Ludwig
T1  - Wettability, surface morphology and stability of long chain ester multilayers obtained by different Langmuir- Blodgett deposition type
Y1  - 1994
ER  - 
TY  - JOUR
A1  - Schulz, Burkhard
A1  - Stiller, Burkhard
A1  - Zetzsche, Thomas
A1  - Knochenhauer, Gerald
A1  - Dietel, Reinhard
A1  - Brehmer, Ludwig
T1  - Crystal structure of 2,5-Di(4- methoxycarbonyl-phenyl)-1,3,4-oxadiazole characterized by AFM and IR- spectroscopy
Y1  - 1994
ER  - 
TY  - JOUR
A1  - Schulz, Burkhard
A1  - Knochenhauer, Gerald
A1  - Brehmer, Ludwig
A1  - Janietz, Silvia
T1  - Stuctures and properties of aromatic poly(1,3,4-oxadiazole)s
Y1  - 1994
ER  - 
TY  - JOUR
A1  - Brehmer, Ludwig
A1  - Hahn, M.
A1  - Seifert, M.
A1  - Wernecke, R.
A1  - Jäger, Werner
A1  - Wonnenberg, R.
A1  - Zehner, C.
T1  - Verfahren zur Herstellung eines Feuchtsensor
Y1  - 1994
ER  - 
TY  - JOUR
A1  - Grasnick, G.
A1  - Herkner, G.
A1  - Katholy, Stefan
A1  - Brehmer, Ludwig
T1  - Pyroelektrisches Dünnschichtelement
Y1  - 1994
ER  - 
TY  - JOUR
A1  - Brehmer, Ludwig
A1  - Hahn, M.
A1  - Seifert, M.
A1  - Wernecke, R.
A1  - Jäger, Werner
A1  - Wonnenberg, R.
A1  - Zehner, C.
T1  - Feuchtesensor
Y1  - 1994
ER  - 
TY  - JOUR
A1  - Angelova, Angelina
A1  - Ionov, Radoslav
A1  - Reiche, Jürgen
A1  - Brehmer, Ludwig
T1  - Head-to tail or head-to-head structure of Langmuir-Blodgett long chain ester multilayers?
Y1  - 1994
ER  - 
TY  - JOUR
A1  - Brehmer, Ludwig
T1  - Dünne organische Schichten : Anforderungen und Möglichkeiten für die Sensorik
Y1  - 1994
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Kamusewitz, Helmut
A1  - Keller, Manuela
A1  - Brehmer, Ludwig
A1  - Peñacorada, Florencio
T1  - Study of gas transport through composite membranes with a stabilised Langmuir-Blodgett skin layer
N2  - 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.
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Angelova, Angelina
A1  - Reiche, Jürgen
A1  - Ionov, Radoslav
A1  - Janietz, Dietmar
A1  - Lemmetyinen, Helge
A1  - Brehmer, Ludwig
T1  - Control of the structure of Langmuir-Blodgett films of a discotic liquid crystalline compound via the subphase composition and the adjacent molecular environment
N2  - 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.
Y1  - 1994
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Penacorada, Florencio
A1  - Geue, Thomas
A1  - Pietsch, Ullrich
A1  - Brehmer, Ludwig
T1  - Monolayers and multilayers of uranyl arachidate : in-plane structure of uranyl arachidate multilayers
N2  - 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.
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Knochenhauer, Gerald
A1  - Dietel, Reinhard
A1  - Freydank, Anke-Christine
A1  - Zetzsche, Thomas
A1  - Pietsch, Ullrich
A1  - Brehmer, Ludwig
A1  - Barberka, Thomas Andreas
A1  - Geue, Thomas
T1  - Structure of thermally treated oxadiazoleamide Langmuir-Blodgett films
N2  - 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.
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Penacorada, Florencio
A1  - Reiche, Jürgen
A1  - Zetzsche, Thomas
A1  - Dietel, Reinhard
A1  - Brehmer, Ludwig
A1  - Saja, Jose-Antonio de
T1  - Stabilisation of fatty acid mono- and multilayers by simultaneous polyelectrolyte complexation and salt formation with cadmium ions
N2  - 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.
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Schulz, Burkhard
A1  - Knochenhauer, Gerald
A1  - Dietzel, Birgit
A1  - Freydank, Anke-Christine
A1  - Zetzsche, Thomas
A1  - Brehmer, Ludwig
T1  - Supramolecular structures formed from heterocyclic aromatic molecules
N2  - 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.
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Papra, Alex
A1  - Penacorada, Florencio
A1  - Reiche, Jürgen
A1  - Katholy, Stefan
A1  - Brehmer, Ludwig
A1  - Hicke, Hans-Georg
T1  - Structure and Stability of Langmuir Monolayers and Langmuir-Blodgett Films of Bisaroyl Azide Bolaamphiphiles
N2  - 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
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Penacorada, Florencio
A1  - Reiche, Jürgen
A1  - Dietel, Reinhard
A1  - Zetzsche, Thomas
A1  - Stiller, Burkhard
A1  - Knobloch, Harald
A1  - Brehmer, Ludwig
T1  - Monolayers and multilayers of uranyl arachidate : 2. Influence of the subphase pH on the structure and stability of Langmuir-Blodgett films
N2  - 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.
Y1  - 1996
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Brehmer, Ludwig
T1  - Einfluss des Transferverhältnisses auf die Monoschichtsymmetrie in Y-Typ Langmuir-Blodgett-Schichten
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Schulz, Burkhard
A1  - Brehmer, Ludwig
T1  - Preparation and characterization of ordered thin films based on aromatic poly(1,3,4-oxadiazole)s
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Schulz, Burkhard
A1  - Brehmer, Ludwig
A1  - Knochenhauer, Gerald
T1  - Supramolecular structures of aromatic 1,3,4-oxadiazole solids
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Katholy, Stefan
A1  - Reiche, Jürgen
A1  - Brehmer, Ludwig
T1  - Strukturuntersuchungen an Langmuir-Monoschichten organischer Amphiphile mittels Brewsterwinkelmikroskopie
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Stephan, Jörg
A1  - Liemant, Alfred
A1  - Albrecht, Fred
A1  - Brehmer, Ludwig
T1  - Interplay of polaronic and disorder effects on electronic charge transport
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Stephan, Jörg
A1  - Schrader, Sigurd
A1  - Brehmer, Ludwig
T1  - Monte Carlo simulations of charge transport in molecular solids : a modified Miller Abrahams type jump rate approach
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Stephan, Jörg
A1  - Brehmer, Ludwig
T1  - Dynamic Monte Carlo simulation of organic molecular beam deposition: influence of growth parameters on film morphology
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Kaminorz, Yvette
A1  - Smela, Elisabeth
A1  - Johansson, Tomas
A1  - Brehmer, Ludwig
A1  - Andersson, Mats R.
A1  - Inganäs, Olle
T1  - Characteristics of polythiophene surface light emitting diodes
N2  - Surface light emitting diodes SLEDs , in which previously microfabricated electrodes were coated with a conjugated polymer, were made with greatly different electrode spacings 250 nm and 10 or 20 mm and with different electrode material combinations. The fabrication process allowed us to compare several electrode materials. The SLED structures also enabled imaging of the light emission zone with fluorescence video microscopy. Conventional sandwich structures were also made for comparison electrode separation 50 nm. In this study, the emitting layer was poly[3- (2',5'-bis(1'',4'',7''trioxaoctyl)phenyl)-2,2'-bithiophene] (EO-PT), a conjugated polymer based on polythiophene with oligo ethyleneoxide side chains. The current-voltage (I(V)) and light-voltage (L(V)) characteristics of the SLEDs were largely insensitive to electrode separation except at high voltages, at which the current in the devices with the largest separations was limited. Sandwich structures had the same light output at a given current. Light could be obtained in forward and reverse bias from indium tin oxide ITO -aluminum, gold silicide-aluminum, and gold silicide-gold SLEDs, but the turn-on voltages were lowest with the ITO-aluminum devices, and these were also the brightest and most reliable. Adding salt to the EO-PT increased the current and brightness, decreased the turn-on voltages, and made the I(V) characteristics symmetric; thus, a device with an electrode separation of 10 mm had the extraordinarily low turn-on voltage of 6 V. The location of the light emission was at the electron-injecting contact.
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Wüstneck, Rainer
A1  - Prescher, Dietrich
A1  - Katholy, Stefan
A1  - Knochenhauer, Gerald
A1  - Brehmer, Ludwig
T1  - Surface dilatational rheological study of the trans-cis isomerisation of copolymers with trifluoromethoxy substituted metacrylate monolayers
Y1  - 2000
SN  - 0927-7757
ER  - 
TY  - JOUR
A1  - Kaminorz, Yvette
A1  - Schulz, Burkhard
A1  - Brehmer, Ludwig
T1  - Optical and Electrical Properties of Substituted 2,5-Diphenyl-1,3,4-Oxadiazoles
N2  - New substituted 2,5-diphenyl-1,3,4-oxadiazoles are reported as luminescent materials in light emitting diodes LEDs . The investigated new oxadiazoles show efficient blue and green emission in single layer devices. The combination with a hole transporting and red emitting polythiophene led to a white emission with higher quantum efficiency (QE).
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Karageorgiev, Peter
A1  - Stiller, Burkhard
A1  - Prescher, Dietrich
A1  - Dietzel, Birgit
A1  - Schulz, Burkhard
A1  - Brehmer, Ludwig
T1  - Modification of the surface potential of azobenzene-containing langmuir-blodgett films in the near field of a scanning kelvin microscope tip by irradiation
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Stiller, Burkhard
A1  - Karageorgiev, Peter
A1  - Perez, E.
A1  - Valez, M.
A1  - Reiche, Jürgen
A1  - Prescher, Dietrich
A1  - Dietzel, Birgit
A1  - Brehmer, Ludwig
T1  - Scanning kelvin microscopy as a tool for visualisation of optically induced molecular switching in azobenzene self assembling films
Y1  - 2000
SN  - 0142-2421
ER  - 
TY  - JOUR
A1  - Stiller, Burkhard
A1  - Köpnick, Thomas
A1  - Muzikante, I.
A1  - Neilands, O.
A1  - Utinans, M.
A1  - Dubrovich, O.
A1  - Karageorgiev, Peter
A1  - Brehmer, Ludwig
T1  - Optically induced switching effect of polymer containing indandione-1,3-pyridinium betaine side chains
Y1  - 1999
SN  - 0378-2271
ER  - 
TY  - JOUR
A1  - Gustina, D.
A1  - Markava, E.
A1  - Muzikante, I.
A1  - Stiller, Burkhard
A1  - Brehmer, Ludwig
T1  - Photoisomerisation process of self-assembled monolayers of some novel azobenzenes
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Giebler, Rainer
A1  - Schulz, Burkhard
A1  - Reiche, Jürgen
A1  - Brehmer, Ludwig
A1  - Wühn, Mario
A1  - Wöll, Christoph
A1  - Smith, Andrew Phillip
A1  - Urquhart, Steven G.
A1  - Ade, Harald W.
A1  - Unger, Wolfgang E. S.
T1  - Near-edge x-ray absorption fine structure spectroscopy on ordered films of an amphiphilic derivate of 2,5- Diphenyl-1,3,4-oxadiazole
N2  - 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.
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Brehmer, Ludwig
T1  - Ultrathin films for senorics and molecular electronics
Y1  - 1999
SN  - 3-540-65487-9
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Freydank, Anke-Christine
A1  - Helms, Andreas
A1  - Geue, Thomas
A1  - Schulz, Burkhard
A1  - Brehmer, Ludwig
A1  - Stiller, Burkhard
A1  - Knochenhauer, Gerald
T1  - Vacuum deposition films of oxadiazole compounds : formation and structure investigation
N2  - 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.
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Knochenhauer, Gerald
A1  - Penacorada, Florencio
A1  - Reiche, Jürgen
A1  - Brehmer, Ludwig
A1  - Tredgold, Richard H.
A1  - Barberka, Thomas Andreas
T1  - Multilayers of perfluorinated fatty acids
N2  - 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.
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Höpfner, Ulf
A1  - Hehl, H.
A1  - Brehmer, Ludwig
T1  - Preparation of ordered thin gold films
Y1  - 1999
ER  -