  Single-shot absorption measurements have been performed using the multi-keV
X-rays generated by a laser wakefield accelerator. A 200 TW laser was used to
drive a laser wakefield accelerator in a mode which produced broadband electron
beams with a maximum energy above 1 GeV and a broad divergence of $\approx15$
miliradians FWHM. Betatron oscillations of these electrons generated
$1.2\pm0.2\times10^6$ photons/eV in the 5 keV region, with a signal-to-noise
ratio of approximately 300:1. This was sufficient to allow high-resolution
XANES measurements at the K-edge of a titanium sample in a single shot. We
demonstrate that this source is capable of single-shot, simultaneous
measurements of both the electron and ion distributions in matter heated to eV
temperatures by comparison with DFT simulations. The unique combination of a
high-flux, large bandwidth, few femtosecond duration X-ray pulse synchronised
to a high-power laser will enable key advances in the study of ultra-fast
energetic processes such as electron-ion equilibration.
