Ultrafast nonlinear spectroscopy of molecular shock compression

Dana D. Dlott, School of Chemical Sciences, University of Illinois at Urbana Champaign

This work is focused on understanding molecular shock compression at a fundamental level. In order to make a good connection to simulations, it is desirable to probe shock compression with high temporal and spatial resolution. We have combined femtosecond laser shock wave generation with a nonlinear spectroscopy probe technique termed "vibrational sum-frequency generation" spectroscopy (SFG). Since SFG selectively probes molecular structures at interfaces and surfaces, we are able to study shock compression of molecules with picosecond time resolution and angstrom spatial resolution. We can watch the dynamics of a plane of methyl groups 1.5 angstrom thick during shock compression. These experiments are interpreted with the help of extensive molecular simulations.

We have also used SFG to look at the surfaces of energetic materials and binder materials. Some preliminary results will be discussed that look at the surfaces of HMX and estane and interface between them.

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