Chemical Microscopy of Surfaces by Sum Frequency Generation Imaging

Sum frequency generation imaging microscopy has been developed and implemented in different systems from self-assembled monolayer on metal surfaces to reaction of a metal surface upon exposure to a corrosive material (cyanide solution). It also helped the fundamental issues of heterogeneity to be understood by using mapping analysis that considers an acquired spectrum in a chosen region-of-interest to be independent of its neighboring ROIs. The construction of the microscope has been utilized and modified to accommodate the improvement of its spatial resolution, signal-to-noise ratio, and faster accumulation time. The latter aspect is more dependent toward the kind of sample to be analyzed. Finally, the current resolution of this diffraction-limited microscope is similar to 2 mu m and there is still some room for improvement to reach its ultimate resolution of similar to 800 nm. The main and final goal of this study is to provide chemical sensitivity, interfacial specificity, and a two-dimensional image based on the chemical properties of the adsorbed molecules on the surface and also the substrate itself.