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 (ΔE/E ∼ 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 µm. 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 © 2009 John Wiley & Sons, Ltd.