Liquid Structure of Carbon and Hydrocarbons around 100 GPa and 5000 K

Structural properties of liquid carbon and hydrocarbons at extreme pressures and temperatures are highly relevant for modelling the interiors of carbon-bearing planets as well as modern inertial confinement fusion concepts where plastic or carbon are used as ablator materials. Here we present dynamic compression experiments performed at the Linac Coherent Light Source that allow for experimentally determining the high-pressure liquid structure of these materials with high precision. We show that liquid carbon is dominated by a diamond-like structure close to the melting line. These strong carbon-carbon interactions lead to partial demixing in hydrocarbon samples at similar conditions.