In-Situ SPECTROSCOPIC PROBE OF SOLID AND LIQUID INTERFACES IN COLLOIDAL SOLUTIONS
Second-order non-linear optical techniques, such as Second Harmonic Generation (SHG) and Sum Frequency Generation (SFG) selectively probe the interface region between centrosymmetric bulk media. Experiments that use these nonlinear optical methods to probe chemical and physical processes at liquid and solid interfaces will be described. The focus here is the recent discovery of SHG and SFG generation from the interfaces of micro- and colloidal particles in centrosymmetric bulk media. The application of this new technique is able to provide insight in understanding interfacial phenomena of many environmentally, biologically, and industrially important micro-particle and colloidal systems, such as, polymer beads, emulsions, semiconductor colloids, liposomes, and vesicles, etc.