Two-dimensional X-ray photoelectron spectroscopy for composite surface analysis.

We describe a method for obtaining two-dimensional X-ray photoelectron spectroscopic data derived from the frequency dependence of the XPS peaks recorded under electrical square-wave pulses, which control and affect the binding energy positions via the electrical potentials developed as a result of charging. By using cross-correlations between various peaks, our technique enables us to elucidate electrical characteristics of surface structures of composite samples and bring out various correlations between hidden/overlapping peaks.