Berlin 2008 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 9: POSTERS Single Molecules, Biopolymers, Membranes

CPP 9.24: Poster

Montag, 25. Februar 2008, 16:45–19:00, Poster A

Temperature dependent (2D) ordering in monolayers of amphiphile molecules — •Saskia Schmacke¹, Bernd Struth², Lutz Wiegart³, Henri Gleyzolle³, Michael Paulus¹, and Metin Tolan¹ — ¹Fakultät Physik /DELTA, Technische Universität Dortmund, D-44221 Dortmund, Deutschland — ²DESY, D-22602 Hamburg, Deutschland — ³ESRF, B.P. 220, 38043 Grenoble Cedex, France

Layers of amphiphile molecules on liquid substrates show a different phase behaviour depending on environmental parameters such as temperature, surface pressure and subphase. In this work the solid phase of the Phospholipid monolayer DPPC (dipalmitoyl-glycerophosphocholine) was analysed in order to investigate the influence of temperature on the crystaline structure of the layer. The latter was determined by the use of the Gracing Incidence X-Ray Diffraction technique (GID) at the beamline ID10b, ESRF. The obtained diffraction spectra are analysed in two steps: First the information about the 2D unit cell of the crystalline phase, e.g. lattice spacings, lattice type (2D Bravais lattice) and the deformation of the lattice was determined. In the second step the intensity dependence on the wave vector transfers perpendicular to the surface was analysed leading to information about the scatterer itself. Thus, chain length, diameter, tilt angle and orientation within the lattice of the molecules forming the monolayer are determined. A temperature induced phase transition from a centred rectangular to a hexagonal lattice with decreasing temperature was observed.