9313820 Neuman A Surface force microscope equipped with silica surfaces and laser spectroscopic attachments will be used to simultaneously study the tribological properties of molecularly thin liquid films and the behavior of the molecules in the liquid. The techniques of sum-frequency generation and flourescence recovery after photobleaching will be used to independently measure molecular orientation, mobility, interacions with the surface, and relaxation. These properties will be correlated with stick- slip transitions, shear stress and rheology of the thin film. The liquids to be tested include perflouropolyether and n- hexadecane with and without phisisorbed and chemisorbed additives. Part of the work will be performed in cooperation with the Swedish Institute for Surface Chemistry in Stockholm. ***