Micromanipulation of Langmuir-monolayers with optical tweezers

A technique for the manipulation of Langmuir-monolayers at the air/water in terface is presented. Optical tweezers are combined with fluorescence and B rewster angle microscopy to produce a system capable of mechanical and ther mal handling of monolayers on a micrometer scale. The viscoelastic, electri cal, and thermodynamic properties of the monolayer can be determined by ana lysis of the perturbations of its structure. A method for force and heat ca libration of the tweezers is given. Both kinds of micromanipulations are ap plied to the star shaped condensed domains in liquid expanded surroundings of bis[8-(1,2-dipalmitoyl-snglycero-3 -phosphoryl)-3,6-dioxaoctyl]disulfide ("thiolipid") monolayers. The stability of the stars and the consequence o f their interlocking on the interfacial flow are investigated.