X-Ray Crystal Spectroscopy of Sub-picosecond Laser-Produced Plasmas beyond 50 keV.

The interaction of a sub-picosecond (sub-ps) laser with a high-Z target produces a hard x-ray continuum, but to our knowledge no high-resolution study of the line emission is known. We present here crystal spectroscopy as a tool for the observation of energetic line x-radiation from a sub-ps laser-produced plasma. Reflection properties of flat and bent crystals for x-ray spectroscopy are analyzed theoretically for both the Bragg and the Laue geometries and optimized for a crystal spectroscopy of hard (>50 keV) x-radiation. The crystal setup is optimized for spectroscopic applications with regard to high throughput and spectral resolution. The characteristic tantalum Kα,β- and Lα,β-line emissions from a sub-ps laser-produced plasma is observed for the first time. A resolving power of about 450 is achieved which is much higher than that for comparable absorption filter techniques (E/ΔE ≈ 15).