Tripelpunktbenetzung in zweidimensionalen dipolaren Langmuir Filmen

• Applicant: Professor Dr. Mathias Lösche
• Subject Area: Experimental Condensed Matter Physics
• Term: from 1998 to 2003
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5107472

Two dimensional wetting phenomena within Langmuir monolayers at the air/water-interface are investigated in the three-phase coexistence region liquid condensed/liquid expanded/gas using fluorescence microscopy, optical tweezers and grazing incidence X-ray diffraction. Using methyl-octadecanoate as a model we determine, whether boundary stabilization of the quasi-2D-phases is responsible for the observation of 3-phase coexistence over an extended range within the lateral pressure vs. Temperature phase diagram. Our hypothesis, based on the work of Möhwald and McConnell, is that electrostatic interactions and line tensions between the phases determine the wetting patterns within the monolayers. Surface potentials of the phases, line tension between the phases and the cutoff length of the dipoledipole interaction in terms of the nearest neighbor distances between the film forming molecules are the important parameters within the framework of the model and will be measured to find out, which one is responsible for the dewetting transition of LE droplets from the LC/G boundary.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1052: Benetzung und Strukturbildung an Grenzflächen
• Major Instrumentation: Brewsterwinkelmikroskop
• Instrumentation Group: 5040 Spezielle Mikroskope (außer 500-503)
• Participating Person: Professor Dr. Thomas Martin Fischer