Au 4f spin–orbit coupling effects in supported gold nanoparticles

Abstract

Using X-ray photoelectron spectroscopy we examine the Au 4f spin–orbit components in Au 4f spectra of nanosized Au particles on a TiO₂ support. In general, the peak ratios of the Au 4f_7/2 and 4f_5/2 excitations are found to deviate from the statistical ratio of 4 : 3 and their linewidths (FWHM) are not equal. We reveal that both the FWHM and the Au 4f_7/2-to-4f_5/2 peak ratios increase appreciably as the Au atomic concentration on the surface of the TiO₂ support and the size of Au nanoparticles decrease. On the contrary, the Au 4f spin–orbit splitting remains essentially unchanged. Our findings are discussed in terms of alterations in the electronic band structure.