The Fourier Transform Infrared Spectrometer (FTIR) Attenuated Total Reflectance (ATR) capability purchased with this award will be used primarily for three projects: (1) thickness determination of thin-film composite membranes for gas separations, (2) determination of crosslink density and its variation with depth for thin-gel composite membranes for bioseparations, and (3) determination of the mechanisms of interfacial polycondensation. The latter two projects are novel applications that take advantage of the depth-profiling capability of ATR-FTIR spectroscopy. Thin film, solution-diffusion, composite membranes are an attractive and versatile alternative to integrally-skinned asymmetric membranes. In-situ, interfacial polycondensation is one method of producing the selective film and has been used to produce composite membranes for reverse osmosis. It is currently being used to produce thin-film composite membranes for gas separations and thin-gel composite membranes. The ATR-FTIR capabilities will greatly improve the productivity of the group working on these projects.