Figure 13.
(Color online) For application of SESSA to predict the signal strengths from SAM-coated Au nanoparticles, the particles were modeled as multiconcentric cylinders, where each cylinder surface has an average photoelectron take-off angle of ai. The XPS detector is positioned at 0° from the central axis of the AuNP. (a) The sphere is divided into nine concentric cylinders. (b) The end of each cylinder is modeled as a flat surface tiled relative to the axis of the spectrometer with infinite thickness of gold, and (c) the surface composition of each flat Au sample is weighted by its geometric factor then summed together to find the AuNP surface composition. Reprinted with permission from Techane et al., Anal. Chem. 83, 6704 (2011). Copyright 2011, American Chemical Society.