Femtosecond high-resolution hard X-ray spectroscopy using reflection zone plates

An off-axis total external reflection zone plate is applied to wavelength-dispersive X-ray spectrometry in the range from 7.8 keV to 9.0 keV. The resolving power E/Delta E of up to 1.1x10(2), demonstrated in a synchrotron proof-of-concept experiment, competes well with existing energy-dispersive instruments in this spectral range. In conjunction with the detection efficiency of (2.2 +/- 0.6)%, providing a fairly constant count rate across the 1.2 keV band, the temporal pulse elongation to no more than 1.5 x 10(-15) s opens the door to wide-range, ultra-fast hard X-ray spectroscopy at free-electron lasers (FELs). (C) 2015 Optical Society of America