Bent silicon crystal in the Laue geometry to resolve x-ray fluorescence for x-ray absorption spectroscopy

Abstract

A highly strained, curved silicon crystal in the Laue geometry has been used as a large-area x-ray fluorescence analyzer for x-ray absorption spectroscopy. The analyzer is able to resolve the Lα fluorescence lines for neighboring actinide elements. A large gain in the signal to background ratio has been demonstrated for small quantities of Np in the presence of U, with the U fluorescence peak approaching 1000 times the magnitude of the off-peak background.

Yucca Mountain project : FY 2006 annual report for waste form testingactivities.

“…This is confirmed by recent x-ray absorption near-edge spectroscopy (XANES) studies that indicate the oxidation state of Np in the fuel matrix is Np(IV) and extended x-ray absorption fine structure (EXAFS) measurements that show the Np(IV) is present in a UO 2 -like phase. This is consistent with Np being in solid solution in the fuel's UO 2 fluorite lattice structure (Kropf et al 2005, Argonne 2005; see also this report, Section 3.4).…”

Fast-scanning high-flux microprobe for biological X-ray fluorescence microscopy and microXAS

“…Bent crystal Laue analyzers (BCLAs) are alternative detection systems for these special and very limited cases. They cover absorption edges from Fe to Zn (Zhong et al, 1999;Kropf et al, 2003Kropf et al, , 2005. These analyzers offer a high background rejection and high energy resolution (up to $ 3.3 eV at 6.9 keV for our customdesigned BCLA for Ni, Cu and Zn spectral lines).…”

High resolution short focal distance Bent Crystal Laue Analyzer for copper K edge x-ray absorption spectroscopy

“…Zhong's and Kropf's devices were limited to higher energies because the absorption of the fluorescence photons by the ∼140-200 microns thick crystal used. The need of thinner crystals for low energies down to 5 KeV was proposed by Kropf et al 8 but not reported before. Our device was designed for thin crystals to cover a lower energy range near Cu K lines.…”

“…Previously, a BCLA device reported by Zhong et al 6 showed that this type of bending could be used for x-ray spectroscopy determinations for energies above 13 keV although their device lack soller slits that could reject the unwanted transmitted beam. Later, Kropf et al 8 developed a BCLA that incorporated soller slits, improving energy resolution, but not sufficient to resolve Kα 1 and Kα 2 lines in that energy range. Zhong's and Kropf's devices were limited to higher energies because the absorption of the fluorescence photons by the ∼140-200 microns thick crystal used.…”

“…In recent years an alternative approach for wavelength dispersive detectors has been proposed by applying thin crystal analyzers bent in a log spiral configuration. [6][7][8] The so called Bent Crystal Laue analyzers (BCLA) are commonly a) Author to whom correspondence should be addressed. Electronic mail:…”