Using optical tweezing to control phase separation and nucleation near a liquid–liquid critical point

About 20 years ago, it was shown that lasers can nucleate crystals in super-saturated solutions and might even be able to select the polymorph that crystallises. However, no theoretical model was found explaining the results and progress was slowed down. Here we show that laser-induced nucleation ma...

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Bibliographic Details
Published inSoft matter Vol. 15; no. 41; pp. 8279 - 8289
Main Authors Walton, Finlay, Wynne, Klaas
Format Journal Article
LanguageEnglish
Published Cambridge Royal Society of Chemistry 2019
Subjects
Critical point
Crystals
Lasers
Nucleation
Phase separation
Thermophoresis
Variation
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Summary:About 20 years ago, it was shown that lasers can nucleate crystals in super-saturated solutions and might even be able to select the polymorph that crystallises. However, no theoretical model was found explaining the results and progress was slowed down. Here we show that laser-induced nucleation may be understood in terms of the harnessing of concentration fluctuations near a liquid–liquid critical point using optical tweezing in a process called laser-induced phase separation (LIPS) and LIPS and nucleation (LIPSaN). A theoretical model is presented based on the regular solution model with an added term representing optical tweezing while the dynamics are modelled using a Kramers diffusion equation, and the roles of heat diffusion and thermophoresis are evaluated. LIPS and LIPSaN experiments were carried out on a range of liquid mixtures and the results compared to theory.
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ISSN:1744-683X
1744-6848
1744-6848
DOI:10.1039/C9SM01297D