Investigating crystal nucleation and growth under the influence of optical tweezers

Flannigan, James and Sefcik, Jan and Haw, Mark (2022) Investigating crystal nucleation and growth under the influence of optical tweezers. In: CMAC Annual Open Day 2022, 2022-05-16 - 2022-05-18.

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Abstract

Optical tweezers allow crystallisation from solution to be localised to a known position within a solution within a relatively well-known timeframe [1]. However, the impact optical tweezers can have on crystallisation still requires investigation. Depending upon the makeup of the solution under investigation, this can result in significant localised heating surrounding the tweezing focal volume [2]. One commonly used way to minimise this temperature rise in aqueous solutions is to use deuterium oxide. However, since this is not the standard isotopologue of water, the fundamental impacts that this would have on bulk crystallisation have not been previously detailed beyond solubility. Investigations show a reduction in the primary nucleation rate. Crystal growth from supersaturated solution can be enhanced locally through the presence of an optical tweezing focus even a relatively low powers. However, the localised growth of a macroscopic crystal can also be inhibited by using regular water and a laser wavelength known to be highly absorbing at a high enough power. The presence of a trapped silica particle appears to prevent the tweezers from being able to increase the growth of a crystal close to the focus in conditions where growth would be enhanced in the absence of the silica particle. At higher laser powers, the focus can directly induce nucleation from solution even in undersaturated conditions when near a solution-air interface. But when moving into the bulk of the solution, the ability to nucleate from the solution diminishes with increasing distance between the interface and the droplet edge. Future work will explore the impact that commonly used tweezing particles have on primary nucleation characteristics, and the effect that holding particles within the focus of the tweezers have on their ability to influence nucleation directly.

ORCID iDs

Flannigan, James, Sefcik, Jan ORCID logoORCID: https://orcid.org/0000-0002-7181-5122 and Haw, Mark ORCID logoORCID: https://orcid.org/0000-0003-3736-1857;

Persistent Identifier

https://doi.org/10.17868/strath.00081960
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