On-Line Structure Control of Langmuir-Blodgett Films

Fluorescence microscopy studies of layer/substrate interaction during the Langmuir-Blodgett transfer: Fractional condensation and local layer modification in lipid monolayers at the three-phase line

Transfer fluorescence microscopy reveals the substrate-mediated fractional condensation and phase-selective deposition of dipalmitoylphosphatidylcholine (DPPC) and dimyristoylphosphatidylethanolamine (DMPE) monolayers during the LB-transfer. Preferentially the higher ordered liquid-condensed (LC) state is transferred onto the substrate during the transfer of a monolayer in the LC/LE (liquid/expanded) coexistence state on the water subphase. This is manifested in the directly observable attraction of LC-domains towards the three-phase line and observation of a domain-free gap as consequence of the segregation of the fluorescent probe into the floating monolayer adjacent to the three-phase li…

Physisorption Instabilities during Dynamic Langmuir Wetting

Continuous dynamic Langmuir wetting of lipid monolayers can create regular stripe patterns on the solid substrate surface. Monolayers doped with minor amounts of fluorescence dye may be deposited in stripes of alternating high and low dye concentration. In case of pure monolayers stripes are observed with AFM. The striations run normal to the dipping direction and have widths of typically several micrometres and distances varying from 1 to ≈ 100 μm. The stripe widths, distances, and fluorescence contrast depend on deposition speed, surface pressure, substrate surface preparation, and dye concentration. The patterns probably result from physisorption (meniscus) instabilities caused by a feed…