Hard X-ray Generation from ZnO Nanowire Targets in a Non-Relativistic Regime of Laser-Solid Interactions

We present a detailed investigation of X-ray emission from both flat and nanowire zinc oxide targets irradiated by 60 fs 5 x 10(16) W/cm(2) intensity laser pulses at a 0.8 mu m wavelength. It is shown that the fluence of the emitted hard X-ray radiation in the spectral range 150-800 keV is enhanced by at least one order of magnitude for nanowire targets compared to the emission from a flat surface, whereas the characteristic K-proportional to line emission (8.64 keV) is insensitive to the target morphology. Furthermore, we provide evidence for a dramatic increase of the fast electron flux from the front side of the nanostructured targets. We suggest that targets with nanowire morphology may advance development of compact ultrafast X-ray sources with an enhanced flux of hard X-ray emission that could find wide applications in highenergy density (HED) physics.