Nucleation Statistics from Experiments as a Benchmark for Theory and Simulations.

Area of Science:

• Physical Chemistry
• Materials Science
• Condensed Matter Physics

Background:

• Nucleation events govern the transformation of metastable substances but their microscopic details are not fully understood.
• Experimental nucleation rates frequently deviate significantly from theoretical predictions and simulations.
• This discrepancy limits the predictive capabilities of current nucleation theories.

Purpose of the Study:

• To provide an overview of nucleation phenomena.
• To focus on crystallization in representative systems: water, colloids, and Lennard-Jones liquids.
• To highlight the utility of rare-gas liquids as model systems for nucleation theory.

Main Methods:

• General overview of nucleation theory.
• Focus on crystallization in metastable water, colloidal suspensions, and Lennard-Jones liquids.
• Utilizing femtosecond X-ray diffraction experiments on supercooled rare-gas liquids (argon and krypton).

Main Results:

• Femtosecond X-ray diffraction experiments yielded accurate crystal nucleation statistics in supercooled argon and krypton.
• Direct observation of structural defects, such as stacking faults, during nucleation was achieved.
• Rare-gas liquids were confirmed as well-controlled systems for studying nucleation.

Conclusions:

• Rare-gas liquids serve as crucial systems for bridging experimental, simulation, and theoretical approaches to nucleation.
• Advances in experimental techniques provide direct microscopic insights into nucleation processes.
• These findings contribute to a more comprehensive understanding of the fundamental mechanisms of nucleation.