Near- and extended-edge x-ray-absorption fine-structure spectroscopy using ultrafast coherent high-order harmonic supercontinua

Author(s): Popmintchev, D; Galloway, BR; Chen, M-C; Dollar, F; Mancuso, CA; Hankla, A; Miaja-Avila, L; O'Neil, G; Shaw, JM; Fan, G; Alisauskas, S; Andriukaitis, G; Balciunas, T; Muecke, OD; Pugzlys, A; Baltuska, A; Kapteyn, HC; Popmintchev, T; Murnane, MM | Abstract: Recent advances in high-order harmonic generation have made it possible to use a tabletop-scale setup to produce spatially and temporally coherent beams of light with bandwidth spanning 12 octaves, from the ultraviolet up to x-ray photon energiesg1.6 keV. Here we demonstrate the use of this light for x-ray-absorption spectroscopyat the K- and L-absorption edges of solids at photon energiesnear 1 keV. We also report x-ray-absorption spectroscopyin the water windowspectral region (284-543 eV) using a high flux high-order harmonic generation x-ray supercontinuumwith 10^{9} photons/s in 1% bandwidth, 3 orders of magnitude larger than has previously been possible using tabletop sources. Since this x-ray radiation emerges as a single attosecond-to-femtosecond pulse with peak brightness exceeding 10^{26} photons/s/mrad^{2}/mm^{2}/1% bandwidth, these novel coherent x-ray sources are ideal for probing the fastest molecular and materials processes on femtosecond-to- attosecondtime scales and picometer length scales.