Spectrometer with vertical dispersion mode for studying chemical shifts in X-ray emission lines with the use of synchrotron radiation: preliminary experiment

The spectrometer proposed uses white synchrotron radiation for fluorescence excitation. The fluorescence analysis is carried out by a double crystal diffractometer in the vertical dispersion mode. We simulate experimental data taking the uranium Lα1 emission line (ε = 13.6 keV, Δε = 11.3 eV) and Kurchatov Synchrotron Radiation Source parameters. We take into account the following parameters: the partial absorption cross section of the element under investigation μpart(ε), the SR spectral distribution, the Gaussian vertical photon angle distribution σz′ph(ε), and the Gaussian vertical electron linear and angle distributions σzel and σz′el. The emission X-ray line has been taken to have a Lorentz form. The transmission coefficient of the double crystal spectrometer in high dispersion position has been taken to have a Gauss-form σDar. The following results have been achieved. A measurement accuracy Δεε ≅ 10−6 can be achieved when measuring for ∼ 100 s with E = 2.5 GeV and I = 100 mA. Here Δε is the statistic uncertainty of the line position and ϵ is the emission line energy. The natural line width will not be increased by the spectrometer convolutions by more than 20%, so the line form can be investigated very carefully. Based on piezoelectric transducers, the diffractometer is now being commissioned. A preliminary experiment in vertical dispersion mode has been performed and fitted with the theory.