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 - 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 - 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 - Englisch, Uwe A1 - Katholy, Stefan A1 - Penacorada, Florencio A1 - Reiche, Jürgen A1 - Pietsch, Ullrich T1 - Investigation of molecular diffusion across organic multilayers using neutron specular reflectivity Y1 - 1999 ER - TY - JOUR A1 - Englisch, Uwe A1 - Penacorada, Florencio A1 - Samoilenko, I. A1 - Pietsch, Ullrich T1 - Investigation of the vertical molecular exchange in a complex organic multilayer system Y1 - 1998 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 - 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 - 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 - 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 - Reiche, Jürgen A1 - Penacorada, Florencio A1 - Zetzsche, Thomas A1 - Katholy, Stefan A1 - Brehmer, Ludwig T1 - Polyelektrolyt-Fettsäure-Multiphasen-LB-Schichten Y1 - 1995 ER -