The new wave in shock waves

Laser-driven shock waves (0-5 GPa) can be generated at high repetition rates (100/s) using a moderate-energy tabletop picosecond laser system and a multilayered microfabricated shock target array. High spatial resolution is needed to obtain high temporal resolution of the effects of a steeply rising shock front on molecular materials. The needed spatial resolution is obtained using a sandwich arrangement with a thin layer of sample material termed an "optical nanogauge". Experiments with an anthracene nanogauge show that ultrafast vibrational spectroscopy can be used to determine the shock temperature, pressure, velocity, and shock front rise time. Shock pulses can be generated with rise times <25 ps, which generate irreversible shock compression, and with rise times of a few hundred picoseconds, which generate reversible compression. These pulses, which have a duration of a few nanoseconds, are termed "nanoshock" pulses. Nanoshock pulses produce large-amplitude mechanical perturbations and can initiate and turn off thermochemical reactions, produce highly excited vibrational populations, and heat and cool condensed matter systems at tremendous rates. These applications are illustrated briefly in nanoshock experiments on an energetic material and a heme protein. Using high repetition rate nanoshocks to study large-amplitude molecular dynamics in molecular materials important in chemistry and biology is the new wave in shock waves.