Amazing stuff!
"Thanks to new experiments using the DIPOLE 100-X high-performance laser at the European X-ray ... Electron Laser (XFEL) ... has obtained the first detailed view of the microstructure of carbon in its liquid state. The work will help refine models of liquid carbon, enabling important insights into the role that it plays in the interior of ice giant planets like Uranus and Neptune, where liquid carbon exists in abundance. It could also inform the choice of ablator materials in future technologies such as nuclear fusion. ..."
"... Under normal pressure carbon does not melt but immediately changes into a gaseous state. Only under extreme pressure and at temperatures of approximately 4,500 degrees Celsius – the highest melting point of any material – does carbon become liquid. No container would withstand that.
Laser compression, on the other hand, can turn solid carbon into liquid for fractions of a second. And the challenge was to use these fractions of a second to take measurements. In a previously unimaginable way, this has now become reality at the European XFEL, the world’s largest X-ray laser with its ultrashort pulses, in Schenefeld, near Hamburg. ...
The unique combination of the European XFEL with the high-performance laser DIPOLE100-X was crucial for the success of the experiment. ... A community of leading international research institutions at the HED-HIBEF (High Energy Density) experimental station at European XFEL has now combined powerful laser compression with ultrafast X-ray analysis and large-area X-ray detectors for the first time.
In the experiment, the high-energy pulses of the DIPOLE100-X laser drive compression waves through a solid carbon sample and liquefy the material for nanoseconds ... During this nanosecond, the sample is irradiated with the ultrashort X-ray laser flash of the European XFEL. The carbon atoms scatter the X-ray light – similar to the way light is diffracted by a grating. The diffraction pattern allows inferences to be drawn about the current arrangement of the atoms in the liquid carbon.
The whole experiment only lasts a few seconds but is repeated many times: every time with a slightly delayed X-ray pulse or under slightly different pressure and temperature conditions. Many snapshots combine to make a movie. Researchers have thus been able to trace the transition from solid to liquid phase one step at a time. ..."
From the abstract:
"Carbon has a central role in biology and organic chemistry, and its solid allotropes provide the basis of much of our modern technology. However, the liquid form of carbon remains nearly uncharted, and the structure of liquid carbon and most of its physical properties are essentially unknown. But liquid carbon is relevant for modelling planetary interiors and the atmospheres of white dwarfs, as an intermediate state for the synthesis of advanced carbon materials, inertial confinement fusion implosions, hypervelocity impact events on carbon materials and our general understanding of structured fluids at extreme conditions.
Here we present a precise structure measurement of liquid carbon at pressures of around 1 million atmospheres obtained by in situ X-ray diffraction at an X-ray free-electron laser.
Our results show a complex fluid with transient bonding and approximately four nearest neighbours on average, in agreement with quantum molecular dynamics simulations.
The obtained data substantiate the understanding of the liquid state of one of the most abundant elements in the universe and can test models of the melting line.
The demonstrated experimental abilities open the path to performing similar studies of the structure of liquids composed of light elements at extreme conditions."
Structure of liquid carbon measured for the first time (original news release) "With the declared aim of measuring matter under extreme pressure, an international research collaboration headed by the University of Rostock and the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) used the high-performance laser DIPOLE 100-X at European XFEL for the first time in 2023. With spectacular results: In this initial experiment they managed to study liquid carbon – an unprecedented achievement ... "
Groundbreaking experiment at European XFEL: Research team measured structure of liquid carbon for the first time (illustration ...)
Fig. 1: Schematic of the experimental setup.
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