XAFS spectroscopy by an X-ray tube based spectrometer using a novel type of HOPG mosaic crystal and optimized image processing

Abstract

a This paper presents recent achievements in laboratory based instrumentation for X-ray Absorption Fine Structure Spectroscopy (XAFS). The key component of the spectrometer is a HAPG mosaic crystal, which is employed in the von Hamos geometry. Due to the high efficiency of HAPG a low power micro focus X-ray tube can serve as an X-ray source. Besides a description of the spectrometer, the paper covers the treatment of the CCD images in detail. The latter is crucial in order to entirely exploit the potential of the HAPG (Highly Annealed Pyrolitic Graphite) spectrometer. One section is dedicated to applications. As a first kind of application, the concentrations of two different iron species in mixtures are determined. A second kind of typical usage of XAFS is the determination of bond lengths from the EXAFS. This XAFS application is demonstrated with metallic Ni as a reference material.

Johann-type laboratory-scale x-ray absorption spectrometer with versatile detection modes

“…For the aforementioned reasons, laboratory-based spectrometers [2,[6][7][8][9][10][11][12][13][14][15][16] are an interesting option for many applications and they have advanced greatly in energy resolution and throughput. Especially the manufactur- * ari-pekka.honkanen@helsinki.fi ing techniques of bent crystal optics have seen major improvements in recent years [17][18][19][20][21][22][23][24].…”

Insights into structure and dynamics of (Mn,Fe)Ox-promoted Rh nanoparticles

“…Mn K-edge X-ray absorption near edge structure (XANES) spectra were collected using a von Hamos laboratory XAFS spectrometer, 45 which operates in transmission mode. As the source an air-cooled micro focus X-ray tube with a power of 30 W, a spot size of 60 mm and molybdenum as the anode material was used.…”

Laboratory von Hámos X-ray spectroscopy for routine sample characterization

“…Schlesiger et al built an XAS spectrometer based on a HOPG mosaic crystal. 19 Although it could produce both XANES and EXAFS spectra of a Ni foil, it is optimized for lowering the necessary acquisition time but cannot provide enough resolution to resolve the fine structure of the XANES spectra. Kayser et al assembled recently a von Hámos spectrometer for XES with a 0D SDD detector, which can track or scan a specific energy from the analyzer, but does not exploit the potential of the von Hámos geometry.…”