EXAFS measurements at the micrometer-scale spatial resolution using achromatic multilayer-based focusing optics

Spatially resolved EXAFS measurements were performed using micrometer-size x-ray beam produced by achromatic Kirkpatrick-Baez (KB) optical system. The KB mirrors were coated with aperiodic multilayers to increase the collection angle as compared to a total reflection mirror and to provide an energy bandpass (Delta E/E similar to 15%) sufficient to acquire an EXAFS spectrum without having to adjust the mirror during data acquisition. A series of measurements were performed at various absorption edges including Fe and Pt at the ESRF synchrotron bending-magnet beamlines BM5 and BM29 to demonstrate the performance of the system within its design energy range (6-13 keV). In particular, the spectra obtained with and without focusing were compared. The relative variation of the size and the position of the microbeam at the sample never exceeded 7% of the beam nominal size, of the order of 1.5 mu m. The combination of the large energy range available from a bending-magnet source with a microfocused achromatic beam could be particularly interesting as a local probe in tandem with a faster yet lower spatial resolution energy-dispersive EXAFS setup. Copyright (C) 2009 John Wiley & Sons, Ltd.