X-ray absorption fine structure combined with X-ray fluorescence spectrometry. Improvement of spectral resolution at the absorption edges of 9-29 keV

Abstract

X-ray absorption near-edge structure (XANES) suffers from core-hole lifetime broadening at a higher energy absorption edge, such as Sn K (29 keV, ΓK = 8.49 eV). To overcome this problem, emitted Sn Kα1 fluorescence from sample was counted using high-energy-resolution fluorescence spectrometer in the XANES measurements. Experimental energy resolution (5.0 eV) was consistent with theoretical values based on the Rowland configuration of the spectrometer. The absorption edge became steeper compared to conventional spectra. The white-line peak due to SnII species became remarkably sharper and more intense in the Sn Kα1-detecting Sn K-edge XANES for Pt-Sn/SiO2. To support the semiclassical theory of resonant Raman scattering for the explanation of observed elimination of lifetime width, more resolved XANES data at Cu K, Pb L3, and Sn K in this work were convoluted (filtered) with a Lorentzian of each core-hole lifetime width. The processed data resembled generally well corresponding XANES spectrum measured in transmission mode. The verification based on ab initio XANES calculations was also performed. © 2005 American Chemical Society.