Native Oxide Spectra – BE of C (1s)?

This is a series of Side-by-Side Plots of a native oxide, that behaves conductively, and the Adventitious Carbon on its surface.

The C (1s) is peak-fitted, while the native oxide is not peak-fitted. The purpose of this comparison is to highlight the problem that exists when we try to use Adventitious Carbon as a point of reference and to charge reference non-conductive materials.

The key BE to study is the C (1) BE of the Hydrocarbon moiety. When we first learn XPS, we soon analyze true non-conductive insulators and we are taught to use one specific C (1s) BE for the Hydrocarbon moiety. That C (1s) BE ranges from 284.2 eV, to 284.6, to 284.7, to 284.8 or 285.0 eV. Which BE is correct, or most reliable? By reviewing these plots, you will better understand the behavior of the C (1s) of the hydrocarbon moiety in Adventitious carbon. You will also realize the issues that exist when we do or do not use charge compensation (flood gun) on Native Oxides, that appear to behave as a conductive film.

As you review these plots, you will find a few comparisons with Charge Compensation (flood gun) turned ON versus OFF. Please note the BEs shifts and peak-width changes that occur.