COHERENT THZ ELECTROMAGNETIC RADIATION EMISSION AS A SHOCK WAVE DIAGNOSTIC AND PROBE OF ULTRAFAST PHASE TRANSFORMATIONS

EJ Reed and MR Armstrong and KY Kim and JH Glownia and WM Howard and EL Piner and JC Roberts, SHOCK COMPRESSION OF CONDENSED MATTER - 2009, PTS 1 AND 2, 1195, 647-650 (2009).

We present the first experimental observations of terahertz frequency radiation emitted when a terahertz frequency acoustic wave propagates past an interface between materials of differing piezoelectric coefficients. We show that this fundamentally new phenomenon can be used to probe structural properties of thin films. Then, we present molecular dynamics simulations showing that detectable THz frequency radiation can be emitted when a wurtzite structure crystal transforms to a rocksalt structure under shock compression on picosecond timescales. We show that information about the kinetics of the transformation is contained in the time-dependence of the THz field.

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