Shock launching in silicon studied with use of pulsed x-ray diffraction

Multikilobar shocks were launched into a single crystal of (111) silicon coated with 1000 Å of aluminum and a 25-μm transparent plastic layer by irradiation with a 1-nsec pulse of 1.06-μm laser light at 0.8–8 J ${\mathrm{cm}}^{\mathrm{-}2}$. Peak lattice compressions were directly measured and shocked-lattice stresses inferred as a function of irradiance and time by Bragg-diffracting a short (<100 psec) burst of probing x rays through the shock-launching region. Compressions of up to ∼4% were measured, corresponding to stresses of the order of 70 kbar, at irradiances of ∼4×${10}^9$ W ${\mathrm{cm}}^{\mathrm{-}2}$.