Metallization of fluid hydrogen at 140 GPa (1.4 Mbar) by shock compression

Shock compression was used to produce the first observation of a metallic s tate of condensed hydrogen. The conditions of metallization are a pressure of 140 GPa (1.4 Mbar), 0.6 g/cm(3) (ninefold compression of initial liquid- Ha density), and 3000 EC. The relatively modest temperature generated by a reverberating shock wave produced the metallic state in a warm fluid at a l ower pressure than expected previously for the crystallographically ordered solid at low temperatures. The relatively large sample diameter of 25 mm p ermitted measurement of electrical conductivity. The experimental technique and data analysis are described.