Investigating laser control over crystal nucleation

Kinney, Nina L.H. (2020) Investigating laser control over crystal nucleation. MSc(R) thesis, University of Glasgow.

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Abstract

The aim of this project was to investigate the incidence of femtosecond laser-induced crystal nucleation in various compounds, setting the results in context. The search for greater understanding of the mechanisms underlying non-photochemical laser-induced nucleation (NPLIN) and better control over nucleation processes are highly sought after. The following work details the study of laser-induced crystal nucleation in solutions of potassium chloride, glycine and lysozyme to date. Through a comprehensive critical review of the relevant literature, supplemented by an experimental investigation of NPLIN in KCl solutions, the strength of evidence for possible mechanisms underlying this enigmatic phenomenon will be evaluated.

From an overview of the relevant literature, it is clear that evidence for opposing theories of nucleation is developing in parallel, indicating that the existence of multiple mechanisms is likely. The nature of these mechanisms, and factors governing the prevailing mechanism for a given system, leaves much to be explored. This report will contrast observations, in order to shed some light on opposing theories and to identify inconsistencies, where further study is needed.

Experimentally, it was found that femtosecond laser irradiation could successfully induce crystallisation in KCl/D$_{2}$O solutions. The likelihood of NPLIN occurring was found to depend on the saturation value, as expected, and also the laser power. Higher laser powers (with approximately 0.8 W -- 1 W reaching the sample droplet) were found to consistently produce vapour bubbles in heavy water solutions, despite low absorption due to molecular vibrations. The observation of laser-induced bubble formation could be considered an indication that the NPLIN demonstrated resulted from nano- or micro-bubble formation and collapse, as oppose to laser trapping.

All this aims to establish a concrete starting point for the CONTROL project, which seeks to build greater understanding of laser-induced nucleation, with particular emphasis on the consideration of laser-induced liquid-liquid phase separation as a possible precursor to crystal nucleation.

Item Type: Thesis (MSc(R))
Qualification Level: Masters
Keywords: non-photochemical laser-induced nucleation, NPLIN, crystal formation, laser generated bubbles, nano-bubbles, femtosecond, nanosecond, KCl, glycine, lysozyme.
Subjects: Q Science > Q Science (General)
Q Science > QC Physics
Q Science > QD Chemistry
Colleges/Schools: College of Science and Engineering > School of Chemistry
Supervisor's Name: Wynne, Prof. Klaas
Date of Award: 2020
Depositing User: Miss Nina L. H. Kinney
Unique ID: glathesis:2020-82017
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 17 Feb 2021 07:33
Last Modified: 17 Feb 2021 07:56
Thesis DOI: 10.5525/gla.thesis.82017
URI: http://theses.gla.ac.uk/id/eprint/82017

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