Simultaneous measurements of shock velocity and optical reflectance at 1064, 808, and 404 nm of a high pressure shock front propagating through liquid deuterium show a continuous increase in reflectance from below $10\%$ and saturating at $\sim (40–60)\%$ in the range of shock velocities from 12 to $20\mu \mathrm{m}/\mathrm{ns}$ (pressure range 17–50 GPa). The high optical reflectance is evidence that the shocked deuterium reaches a conducting state characteristic of a metallic fluid. Above $20\mu \mathrm{m}/\mathrm{ns}$ shock velocity (50 GPa pressure) reflectance is constant indicating that the transformation is substantially complete.

• Received 9 November 1999

DOI:https://doi.org/10.1103/PhysRevLett.84.5564