Phase matching of the high-order harmonic generation process now makes it possible to produce spatially and temporally coherent ultrafast X-ray beams, with bandwidths spanning more than 12 octaves, from the UV to the keV region. Here we report the first static X-ray absorption spectroscopy at the K- and L-absorption edges of solids in the near-keV range. We also demonstrate X-ray absorption spectroscopy in the water window spectral region (284 541 𝑒𝑉) using an X-ray supercontinuum with high flux (109 𝑝ℎ𝑜𝑡𝑜𝑛𝑠/𝑠 𝑖𝑛 1% 𝑏𝑎𝑛𝑑𝑤𝑖𝑑𝑡ℎ), which is two orders of magnitude larger than has been previously demonstrated. In the future, because this X-ray radiation emerges as an isolated single attosecond-to-femtosecond burst, with peak brilliance exceeding 1026 𝑝ℎ𝑜𝑡𝑜𝑛𝑠/𝑠/𝑚𝑟𝑎𝑑2/𝑚𝑚2/1% 𝑏𝑎𝑛𝑑𝑤𝑖𝑑𝑡ℎ, these novel coherent X-ray sources will be ideal for dynamic probing of the fastest processes in molecules and materials on sub-femtosecond time and picometer length scales.
Citation: Physical Review B
Pub Type: Journals
x-ray absorption, spectroscopy, ultrafast coherent, harmonic supercontinua