Research objectives and content A new type of interfacial rheometer has been built at the Curie Institute and I will use it to study the rheological properties of two-dimensional monolayers. The instrument is based on the optical trapping of micron-size particles and offers features which are not attainable with the rheological macroscopic instruments such as the torsion pendulum viscometer and the canal viscometer. In particular the amplitude of the displacement can be made as low as 100 nm, thus minimizing the mechanically induced distortions of the fragile 2D-structures. Low molecular weight amphiphiles such as fatty acids and long chain silanes represent a case in which I should be able to detect either purely viscous or visco-elastic effects depending on the surface density and the degree of intermolecular cross-linking (2D-polymerization). Long DNA chains will be used to study the effect of transient or permanent entanglements on the monolayer dynamics. Finally the effect of long range positional order will be investigated using polystyrene spheres capable of forming 2D-crystals. From this research I hope to gain a training in at least three different fields: fluid mechanics, physical chemistry of interfaces and surfaces, and optics.