The design and performance of an x-ray emission spectrometer using the polarized Kalpha spectra of chlorine and potassium

The x-ray emission spectrometer was designed to observe the polarization of x-ray fluorescence resulting from the excitation of a sample by synchrotron radiation. The incident photons are intense, monoenergetic and linearly polarized along the plane of the storage-ring orbit. The emission spectrometer records the entire K-α spectrum by dispersing the emitted radiation with a curved Si (111) crystal and detecting the resulting radiation with a resistive anode position sensitive detector; both of which are situated on a Rowland circle. A sample is fixed in position and located in the middle of the Rowland circle. The spectrometer can be positioned to detect fluorescence emitted at 0° and 90° with respect to the polarization/propagation direction of the incident x-rays. In KCl, there was no observable polarization dependence of the emission spectra at the chlorine edge and a large effect seen in potassium below the ionization threshold. There were also small effects seen in freon-13 when excitations were to Rydberg states.