The polarization dependence of x-ray photoelectron yield of a Au photocathode

We report a measurement of the total photoelectron yield of gold as a function of the incident x-ray polarization. Polarized x rays with energies of 2.5, 2.7, and 4.0 keV were used to excite a gold photocathode at a glancing incidence angle between 5° and 50°. Contrary to a previous report, we found no measurable polarization dependence for all three x-ray energies. We conclude that the modulation factor, i.e., the fractional change of the total yield when the polarization state is varied, is less than 4%.