Imaging X-ray fluorescence spectroscopy: laboratory measurements

Following on from the proof-of principle measurements of Martin et al. (X-r ay Spectrom. 28 (1999) 64) we further describe the development of an imagin g X-ray fluorescence (IXRF) spectrometer with no moving parts. Our laborato ry system is based on a microchannel prate (MCP) "lens", a CCD X-ray detect or with good sub-keV quantum efficiency and a conventional electron bombard ment X-ray source. We have used this equipment to form images of a standard XRF target. demonstrating that "elemental maps" (images of the target in t he characteristic X-rays of one particular element) may be formed with sub- millimetre resolution In addition to fluorescent X-rays, we detected X-rays which had been Bragg reflected from the polycrystalline aluminium substrat e of the target. It is possible that the resulting "Bragg images" may be ex ploited to measure spatially varying strain, manifested as lattice distorti on, introduced, for example, by thin films deposited on the surface of a sa mple. (C) 2001 Elsevier Science B.V. All rights reserved.