X-Ray Emission Generated By Laser-Produced Plasmas From Dielectric Nanostructured Targets

We present an experimental study of X-ray generation from nanostructured ZnO targets. Samples of different morphology ranging from nanowires to polished surfaces are irradiated by relativistically intense femtosecond laser pulses. X-ray emission of plasma is generated by 45 fs 130 mJ laser pulses at 400 nm with picosecond temporal contrast better than 10(-9) interacting with an array of ZnO nanowires. The measured spectra indicate the existence of highly ionized states of Zn (up to He-like Zn). The obtained flux of similar to 10(10) photons per laser shot at the neutral Zn K-alpha energies around 8.65 keV and at the Zn He-alpha energies around 9 keV is almost 3 times higher for nanostructured targets compared to the reference polished sample and implies 10(-4) conversion efficiency from the laser energy to the total energy of the emitted X-ray photons.