Ultrafast vibrational spectroscopy of shocks in molecular materials: The first 100 ps

A system which uses a picosecond laser of moderate energy (150 mu J) to generate high repetition rate (100/s) shocks in a monolithic microfabricated shock target array is described. The sample is a molecular material incorporated as a thin layer of the array. Initial results used to characterize the shocks are obtained on polycrystalline anthracene. Coherent Raman spectroscopy is used to determine the shock front risetime (< 25 ps), the shock pressure (4.2 GPa), the shock-induced temperature jump (similar to 350 deg), the shock falltime (1.5 ns), and the shock velocity (similar to 4 km/s). The application of this nanoshock technique to biological materials, specifically the heme protein myoglobin, is discussed briefly.