On the application of two-dimensional correlation spectroscopy to analyze X-ray photoelectron spectroscopic data

The present work focuses on the analysis of X-ray photoelectron spectroscopic (XPS) data by two-dimensional correlation spectroscopy (2D-COS). While it is not useful to perform the generalized form of the 2D-COS analysis on the survey spectra, the later could be used to correlate different regions of the spectra with each other. This correlation leads to useful qualitative information, which is consistent with the underlying physics and chemistry of the studied process and related to the mechanism of perturbation effects on the materials. In addition, the effects of the probing incident X-ray beam on the measured samples are explored. Depending on the chemical structure and stability of the measured samples, the effects of X-ray beam varied from net charging effect on helium irradiated PEEK to massive change in the surface composition of amorphous and proton irradiated PEEK samples. XPS is a sensitive surface analysis technique, and care must be paid to avoid misleading results in the analysis of polymer samples.