Outer sub-shell photoabsorption cross-sections determined by X-ray photoelectron spectroscopy up to 14.5Â keV

 We determined sub-shell photoabsorption cross-sections between 5 and 14.5 keV for the 6s, 5d, 5p, 4f and 5s levels of Au by using the well-established cross-sections of C 1 s as the reference. Spectra were recorded with a commercially available hemispherical analyzer, which we equipped with a pre-retarding lens, allowing us to detect electrons with energies up to 14.5 keV. A comparison with existing relativistic central-field Hartree-Slater calculations reveals that most measured cross-sections are at least twice as large as the theoretical values. In particular, the 6 s derived conduction band electrons have a cross-section almost one order of magnitude larger than given by the (atomic) calculations, which suggests that this may be a solid state effect. These findings are beyond the error of our measurements, which is mostly determined by a lack of precise data for electron escape depths and exact values for the angular anisotropy of electron emission.