Orientation-Insensitive Methodology for Second Harmonic Generation. 2. Application to Adsorption Isotherm and Kinetics Measurements

摘要

In this work, the theory presented in part 1 for an experimental configuration that provides a means to isolate surface surface coverage measurements by SHG from coverage-dependent molecular orientation changes was tested.The adsorption isotherm for disperse red 1 on galss was found to be quite sensitive to the choice of excitaion polarization rotation angle due to a coverage-inendent change in molecular orientation. Appropriateon of the polarization rotation angle, as dictated by meory presented in part 1, yielded reliable adsorption otherm results that were essentially independent of ianges in molecular orientation. Use of a standard iperimental approach (e.g., probing the intensity of-~olarized second harmonic for p-polarized fundamen-resulted in large error (nearly 100%) in the calculatedconstant. The adsorption isotherm for rhod-inune DIX on glass was found to be relatively insensitiveof polarization rotation angle since its irent orientation angle did not change significantly as iunction of coverage.