High pressure insulator-metal transition in molecular fluid oxygen

We report the first experimental evidence for a metallic phase in fluid mol ecular oxygen. Our electrical conductivity measurements of fluid oxygen und er dynamic quasi-isentropic compression show that a nonmetal-metal transiti on occurs at 3.4 fold compression, 4500 K, and 1.2 Mbar. We discuss the mai n features of the electrical conductivity dependence on density and tempera ture and give an interpretation of the nature of the electrical transport m echanisms in fluid oxygen at these extreme conditions.