Possibilities and limitations of synchrotron X-ray powder diffraction with double crystal and double multilayer monochromators for microscopic speciation studies ☆ Wout De Nolf a, ⁎, Jakub Jaroszewicz a , Roberto Terzano b , Ole Christian Lind c , Brit Salbu c , Bart Vekemans d, 1 , Koen Janssens a,2 , Gerald Falkenberg e a Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610, Antwerpen (Wilrijk), Belgium b Dipartimento di Biologia e Chimica Agro-forestale ed Ambientale, Via Amendola 165/A, I-70126, University of Bari, Bari, Italy c Isotope Laboratory, Norwegian University of Life Sciences, PO Box 5003, N-1432 Ås, Norway d Department of Analytical Chemistry, Ghent University, Krijgslaan 281 S12, B-9000 Gent, Belgium e HASYLAB at DESY, Beamline L, Notkestraat 85, D-22603, Hamburg, Germany abstract article info Article history: Received 17 March 2008 Accepted 3 June 2009 Available online 11 June 2009 Keywords: X-ray powder diffraction Multilayer optics Scanning microscopy Synchrotron sources X-ray optics The performance of a combined microbeam X-ray fluorescence/X-ray powder diffraction (XRF/XRPD) measurement station at Hamburger Synchrotronstrahlungslabor (HASYLAB) Beamline L is discussed in comparison to that at European Synchrotron Radiation Facility (ESRF) ID18F/ID22. The angular resolution in the X-ray diffractograms is documented when different combinations of X-ray source, optics and X-ray diffraction detectors are employed. Typical angular resolution values in the range 0.3–0.5° are obtained at the bending magnet source when a ‘pink’ beam form of excitation is employed. A similar setup at European Synchrotron Radiation Facility beamlines ID18F and ID22 allows to reach angular resolution values of 0.1– 0.15°. In order to document the possibilities and limitations for speciation of metals in environmental materials by means of Hamburger Synchrotronstrahlungslabor Beamline L X-ray fluorescence/X-ray powder diffraction setup, two case studies are discussed, one involved in the identification of the crystal phases in which heavy metals such as chromium, iron, barium and lead are present in polluted soils of an industrial site (Val Basento, Italy) and another involved in the speciation of uranium in depleted uranium particles (Ceja Mountains, Kosovo). In the former case, the angular resolution is sufficient to allow identification of most crystalline phases present while in the latter case, it is necessary to dispose of an angular resolution of ca. 0.2° to distinguish between different forms of oxidized uranium. © 2009 Elsevier B.V. All rights reserved. 1. Introduction X-ray powder diffraction (XRPD) is a well established method of phase identification that finds its application in numerous research fields where structural investigation of materials is relevant, such as material science, condensed matter physics and protein crystal- lography. The method can be employed using (high performance) laboratory X-ray sources or at synchrotron end stations. The interest for the use of XRPD as an analytical tool on the micro scale is growing, and an increasing number of X-ray imaging beamlines combine it with X-ray microscopic and spectroscopic techniques [1,2]. At these facilities, an X-ray beam of microscopic dimensions is used to locally excite the sample material while X-ray fluorescence, X-ray absorption and/or X-ray diffraction signals are collected. Recently, the infrastructure at the X-ray fluorescence and spectro- scopy Beamline L at the Hamburger Synchrotronstrahlungslabor (HASYLAB, Hamburg, Germany) has been augmented with an area detector for diffraction measurements. In what follows, the achievable XRPD angular resolution in monochromatic excitation mode [during which a Silicon (111) double crystal monochromator (DCM) is used for energy selection] and in ‘pink’ beam excitation mode [where instead of the DCM a double multilayer monochromator (DMM) is employed] is considered together with the consequences this has for phase identification in materials typically encountered during metal- pollution studies. Since DMMs generally feature a higher throughput than silicon monochromators, shorter exposure times can be achieved, a crucial point in time consuming scanning experiments, where extended series of diffraction patterns are collected from regions-of-interest on a sample. In a first part, this article describes the implementation of the combined scanning micro X-ray fluorescence and micro X-ray Spectrochimica Acta Part B 64 (2009) 775–781 ☆ This paper was presented at the 19th qInternational Congress on X-ray Optics and Microanalysisq (ICXOM-19) held in Kyoto (Japan), 16–21 September 2007, and is published in the Special Issue of Spectrochim. Acta Part B, dedicated to that conference. ⁎ Corresponding author. Tel.: +32 3 2652359; fax: +32 3 2652376. E-mail address: wout.denolf@ua.ac.be (W. De Nolf). 1 Tel.: +32 9 264 48 56; fax: +32 9 264 49 60. 2 Tel.: +32 3 2652373; fax: +32 3 2652376. 0584-8547/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.sab.2009.06.003 Contents lists available at ScienceDirect Spectrochimica Acta Part B journal homepage: www.elsevier.com/locate/sab