Röntgenographische Untersuchungen lateraler Strukturen in molekular dünnen Polyelektrolytfilmen an der Luft Wasser Grenzfläche Röntgenreflektivität Röntgendiffraktion Lamellare Phase Bündelbildung X ray reflectivity X ray diffraction GID lamellar phase bundle formation This work is focused on the detection and analysis of lateral structures in molecular thin polyelectrolyte layers at the air water surface. The aim is to find out the crucial parameters leading to formation and collapse of such structures and influencing the structure properties. Two geometrically different systems are investigated: flatly adsorbed polyelectrolytes and vertically oriented chains within polyelectrolyte brushes. The layers are prepared by spreading appropriate solutions onto the water surface. A langmuir trough is used as an ubiquitous tool to study thermodynamical properties of the samples as well as to adjust the ambient conditions i.e. molecular area lateral pressure temperature or ion content of the subphase and keep them constant during structural analysis ...