Berlin 2005 – wissenschaftliches Programm
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O: Oberflächenphysik
O 15: Postersitzung (Adsorption an Oberfl
ächen, Epitaxie und Wachstum, Organische Dünnschichten, Oxide und Isolatoren, Rastersondentechniken, Zeitaufgelöste Spektroskopie, Methoden)
O 15.6: Poster
Freitag, 4. März 2005, 17:00–20:00, Poster TU D
Neutron Reflectometry from Thin Liquid Layers (Foam Films) — •R. Krastev1,2, Th. Gutberlet3, N. C. Mishra1, and H. Möhwald1 — 1Max-Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany — 2Hahn-Meitner Institute, Berlin, Glienicker Str. 100, 14109 Berlin, Germany — 3Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
The properties of liquids confined in small volumes deviate from that of the bulk material. Foam films have been widely used as model system to study interactions between fluid interfaces but they may be also used as a tool to study the properties of liquids in confined volumes. A foam film is formed by two monolayers of surfactant molecules with the hydrophobic parts facing the air and the hydrophilic head groups in contact with a central aqueous core. Film thickness can be tuned by the physicochemical parameters of the bulk solution from which films are formed while their surfaces always stay parallel each other. This way formation of structures with well defined geometry is assured. We used neutron reflectometry to study the composition of the layers which form a foam film. Films were prepared from solutions of surfactants in D2O. The layers of surfactant and aqueous core were discriminated due to different scattering length densities (SLD). The SLD of the surfactant layers does not depend on the distance between the film surfaces while that of the film central aqueous layer depends on the film thickness. SLD similar to that of D2O was measured in the case of thick films. It decreases when the two surfaces approach each other. The experimental results are shown and future work is discussed.