Measurement of shock wave rise times in metal thin films

We have measured the rise time of laser-generated shock waves in vapor plat ed metal thin films using frequency-domain interferometry with subpicosecon d time resolution. 10%-90% rise times of <6.25 ps were found in targets ran ging from 0.25 to 2.0 mu m in thickness. Particle and average shock velocit ies were simultaneously determined. Shock velocities of similar to 5 nm/ps were inferred from the measured free surface velocity, corresponding to pre ssures of 30-50 kbar. Thus, the shock front extends only a few tens of latt ice spacings.