In situ optical spectroscopy of crystallization: One crystal nucleation at a time

Area of Science:

• Physical Chemistry
• Materials Science
• Spectroscopy

Background:

• Crystal nucleation is fundamental but its microscopic details remain unclear.
• Classical nucleation theory may not fully capture the complexity of nucleation processes.
• Prenucleation aggregates are hypothesized intermediates in crystal formation.

Purpose of the Study:

• To spectroscopically investigate single crystal nucleation events.
• To elucidate the role of prenucleation aggregates in glycine crystallization.
• To explore the structural dynamics of early-stage crystal formation.

Main Methods:

• Implementation of single crystal nucleation spectroscopy (SCNS).
• Combining Raman microspectroscopy with optical trapping induced crystallization.
• Analysis of spectral data using nonsupervised spectral decomposition.

Main Results:

• Identified the Raman spectrum of prenucleation aggregates during single glycine nucleation.
• Demonstrated the critical role of prenucleation aggregates as intermediate species.
• Observed structural order in aggregates through dynamic linear hydrogen-bonded networks.

Conclusions:

• Prenucleation aggregates are crucial intermediates in crystal nucleation.
• The formation of linear hydrogen-bonded networks drives aggregate ordering.
• Optical spectroscopy offers a powerful tool for studying crystal nucleation dynamics.