X-ray photoelectron spectroscopic binding energy shifts due to matrix in alloys and small supported metal particles

Core level binding energies of metals in the following alloys and metal-dispersed or -implanted materials have been studied: AuAg, PtAg, PtC and AuSiO₂. Their shifts from the binding energies of pure species (referenced to the Fermi level) are interpreted to consist of a matrix shift resulting from differences in crystal field potential, relaxation energy and work function as well as a chemical shift due to differences in valence electron density. By estimating the matrix shift using implanted Ar in the related pure materials, the chemical shift could be isolated from the observed binding energy shift. In all cases studied, the matrix shift is greater than the chemical shift and its contribution to the binding energy shifts is in the opposite direction.