Picosecond time-resolved X-ray diffraction from a laser-shocked germanium crystal above Hugoniot elastic limit

Picosecond time-resolved X-ray diffraction has been performed on a 300-ps laser-irradiated germanium crystal at 1.2 GW/cm2. Lattice deformation due to shock compression and the propagation of shock waves are directly observed. The observed lattice compression is 4.3% at maximum, which is higher than that at the Hugoniot elastic limit (HEL). The data suggest that the germanium-crystal lattice behaves elastically under shock compression at 7.5 GPa (above HEL) for 27 ps.