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

Abstract

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 L α1 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 μ part( ε), the SR spectral distribution, the Gaussian vertical photon angle distribution σ z′ph ( ε), and the Gaussian vertical electron linear and angle distributions σ zel and σ z′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 σ Dar. The following results have been achieved. A measurement accuracy Δε ε ≅ 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.