Study of photoemission spectroscopy with polarized x-rays

Several recent experiments were conducted to study the x-ray induced photoemission from solids by polarized x rays for its potential application to stellar x-ray polarimetry. However, it was shown recently that the earlier observed polarization dependence of the secondary photoelectron yield was affected by spurious effects and no polarization dependence could be observed after these spurious effects had been eliminated. Here, we report our first measurement of the primary photoelectrons, i.e., photoelectrons with energy higher than 50 eV. We measured the primary photoelectron yield of a silicon sample as a function of the polarization state of the incident 2.69 keV x-ray beam. We observed that the change of photoelectron yield for different polarization states is especially pronounced around the no-loss photoelectron peaks. This polarization dependency can be explained by the angular distribution of photoelectrons from free atoms excited by polarized x rays. We discuss the experimental results and their implications.