Reconsidering XPS Quantification of Substitution Levels of Monolayers on Unoxidized Silicon Surfaces

In this preprint, we reevaluate the use of X-ray photoelectron spectroscopy (XPS) to determine substitution levels of reactions on non-oxidized silicon surfaces. XPS is the most commonly used method to determine the yields of reactions on surfaces. We go back to the most basic assumptions, and work through the calculations to provide a revised set of calculations that take into account (i) possible adventitious hydrocarbon contamination, (ii) the effect of choosing a different silicon crystal face [Si(100) versus Si(111)], and (iii) the utility of choosing a small heteroatom tag to enable a more accurate measure of substitution levels. We provide a simple algorithm and summary of the equations one can use to make it easy for the reader/researcher.