title: Full-field fluorescence mode micro-XANES imaging using a unique energy dispersive CCD detector.
abstract: X-ray absorption near-edge structure (XANES) spectroscopy is a well-known nondestructive technique that allows for chemical state and local structure determination. Spatially resolved oxidation state imaging is possible performing full-field transmission mode XANES experiments, providing chemical state information on the illuminated sample area, but these experiments are limited to thin, concentrated samples. Here we present the use of a unique energy dispersive (ED) pnCCD detector, the SLcam, for full-field fluorescence mode XANES experiments, thereby significantly relaxing the constraints on sample thickness. Using this new detection methodology, spatially resolved chemical state information on millimeter-sized sample areas can be obtained with microscopic resolution in moderate measuring times (less than 15 h), obtaining a XANES profile for each of nearly 70,000 points in a single measurement without the need of scanning the sample through the beam. Besides a description of the use of this detector for micro-XANES applications, we also present the proof of concept for fluorescence mode micro-XANES using a Fe(0)/Fe2O3 model sample and a Nitisol soil sample, which was measured to obtain iron chemical state distribution information.
authors.affiliation: X-ray Microspectroscopy and Imaging Group (XMI), Ghent University , Krijgslaan 281 S12, B-9000 Ghent, Belgium.
authors.forename: Pieter
authors.initials: P
authors.lastname: Tack
authors.forename: Jan
authors.initials: J
authors.lastname: Garrevoet
authors.forename: Stephen
authors.initials: S
authors.lastname: Bauters
authors.forename: Bart
authors.initials: B
authors.lastname: Vekemans
authors.forename: Brecht
authors.initials: B
authors.lastname: Laforce
authors.forename: Eric
authors.initials: E
authors.lastname: Van Ranst
authors.forename: Dipanjan
authors.initials: D
authors.lastname: Banerjee
authors.forename: Alessandro
authors.initials: A
authors.lastname: Longo
authors.forename: Wim
authors.initials: W
authors.lastname: Bras
authors.forename: Laszlo
authors.initials: L
authors.lastname: Vincze