Atomic and Electronic Structure of Solid-Density Liquid Carbon

Area of Science:

• Materials Science
• Condensed Matter Physics
• Physical Chemistry

Background:

• Understanding the behavior of carbon under extreme conditions is crucial for materials science.
• Previous studies have explored various carbon phases, but high-temperature, high-pressure regimes remain largely uncharted.
• Laser-induced nonthermal melting offers a novel pathway to access these unexplored states.

Purpose of the Study:

• To investigate the dynamics of liquid carbon (l-C) formation via nonthermal melting.
• To analyze the atomic and electronic structure of laser-generated l-C.
• To explore the potential of this method for mapping the carbon phase diagram.

Main Methods:

• Amorphous carbon foil subjected to intense ultrashort laser pulse heating.
• Time-resolved X-ray absorption spectroscopy at the C K edge to monitor melting dynamics.
• Theoretical simulations to complement experimental data.

Main Results:

• Observed subpicosecond electronic structure rearrangement and change in C bonding hybridization during melting.
• Achieved transient equilibrium of l-C at ~14,200 K and ~0.5 Mbar within 0.3 ps.
• Demonstrated a nonthermal melting mechanism leading to solid-density liquid carbon.

Conclusions:

• The laser-induced nonthermal melting technique provides insights into carbon's high-temperature, high-pressure behavior.
• This method enables experimental exploration of previously inaccessible regions of the carbon phase diagram.
• The findings pave the way for future investigations into extreme states of matter.