ENERGETICS AND POPULATION OF MOLECULES AT MICROSCOPIC LIQUID AND SOLID-SURFACES

A new application of second harmonic generation to selectively probe t he surface of microscopic size centrosymmetric structures in centrosym metric bulk media has been applied to polymer beads in aqueous solutio n and to oil droplets in an oil/water emulsion. The free energies of a dsorption and the surface densities of organic molecules adsorbed from aqueous solution to 1 mu m polystyrene bead surfaces and to 230 nm te tradecane oil droplet surfaces have been determined. The potential use of this method as a chemical and biochemical sensor without the need for a fluorescent or magnetic tag is noted.