Fluorescence Yield XAFS measurements by Using the Laboratory X-ray Absorption Spectrometer for Chemical Analysis of Trace Elements

Abstract

X-ray absorption spectroscopy, especially XANES, is one of powerful tool for environmental analysis in various environmental materials such as soil, water, aerosol, and so on. In this paper, it was demonstrated the valence analysis using a laboratory X-ray absorption spectrometer to chromium in the environmental materials as an example. A dried up droplet of aqueous solution of Cr(VI) salt and two urban particulate material standard samples were used as model samples including small amount of Cr. The XANES measurements at Cr K absorption edge was performed by the laboratory apparatus Rigaku R-XAS Looper in fluorescence-yield mode using Ge-SSD or SDD as detector for the Cr K fluorescent X-ray emitted from the measurement samples. The measurement conditions were as follows; 11 kV and 70 mA of tube voltage and current, Ge(220) Johansson-type monochromator, anode and cathode of W, Ne gas sealed proportional counter as incident X-ray beam monitor. As a result, the XANES spectra with enough quality to discriminate chromium with different valence were obtained by using SDD with high energy resolution of 135 eV@5.9 keV although small detection area of 50 mm².