Optical trapping-induced crystallization promoted by gold and silicon nanoparticles

Area of Science:

• Physical Chemistry
• Materials Science
• Nanotechnology

Background:

• Crystallization is fundamental to materials science and chemical processing.
• Controlling crystallization kinetics and polymorph selection remains a significant challenge.
• Nanoparticles offer unique properties for manipulating physical and chemical processes at interfaces.

Purpose of the Study:

• To investigate the promotion of sodium chlorate (NaClO3) crystallization using optical trapping.
• To explore the influence of gold nanoparticles (AuNPs) and silicon nanoparticles (SiNPs) on laser-induced crystallization.
• To elucidate the mechanisms underlying nanoparticle-enhanced crystallization, including plasmonic heating and surface effects.

Main Methods:

• Utilizing optical trapping with a focused laser beam at the air-solution interface of saturated NaClO3 solutions.
• Introducing AuNPs and SiNPs to induce nucleation and growth of metastable NaClO3 (m-NaClO3) crystals.
• Analyzing crystal growth, dissolution cycles, and phase transitions under continuous laser irradiation.
• Comparing the effects of different nanoparticles (AuNPs, SiNPs, polystyrene) on crystallization dynamics.

Main Results:

• Laser-induced aggregation of nanoparticles at the focus promoted nucleation and growth of m-NaClO3.
• AuNPs induced significant size fluctuations in m-NaClO3 crystals due to plasmonic heating.
• SiNPs exhibited more stable crystal behavior compared to AuNPs.
• The maximum diameter of fluctuating m-NaClO3 crystals was consistent across different nanoparticle types and concentrations.
• Polystyrene nanoparticles also promoted crystallization, highlighting the role of particle surface in reducing nucleation activation energy.

Conclusions:

• Optical trapping combined with nanoparticles effectively promotes NaClO3 crystallization.
• Plasmonic heating by AuNPs influences crystal size dynamics, while surface effects are crucial for nucleation.
• The findings offer insights into laser-driven crystallization mechanisms, relevant for materials synthesis and crystal engineering.