Witnessing the birth of a crystal nucleus by non-photochemical laser-induced nucleation

Project Details

Description

Fundamental studies of crystallization are of tremendous importance because of the frequent occurrence of crystallization in nature and its wide use in various industrial processes. In spite of the technological relevance, the initial stages of nucleation are still poorly understood. Major contributing factors to our lack of detailed knowledge include the stochastic nature of nucleation events (solutions nucleate randomly in time), and the difficulty in ensuring homogeneous nucleation (e.g., preventing nucleation on dust or impurities). Not only is there a lack of reliable experimental data, we face the significant computational burden of simulating a growing cluster, particularly in the presence of a solvent. The key aim of this project is to elucidate the microscopic mechanism of crystal nucleation by a new technique called non-photochemical laser-induced nucleation (NPLIN).

Our project objectives are:
(1) Determining conditions of NPLIN for different compound types (ionic, zwitterionic, covalent) and solvents.
(2) Measurement of cluster distributions using dynamic light scattering (DLS) as functions of temperature, saturation, solution history.
(3) Measurement and tracking of large clusters in supersaturated solutions by building a laser scattering microscope (LSM).
(4) In-situ observation of NPLIN monitored by the LSM, including trapping of clusters by laser tweezers.
(5) In-situ micro-Raman spectroscopy of nucleating clusters identified by the LSM.

Layman's description

The growth of solid crystals from liquids is an economically important process, e.g., it is used to produce pharmaceuticals, agrochemicals, fine chemicals, foodstuffs. The moment that a crystal is born is called nucleation. It is a critical process because nucleation determines the number and type of crystal we get. Because nucleation occurs at a random point at a random time, it has been almost impossible to study what happens. Our project uses pulses of laser light to nucleate crystals. We are using this method to study how nucleation arises in order to better understand the nucleation process in general, and also to obtain some control on the quality and type of crystal that comes out.

Key findings

no-return mar13
StatusFinished
Effective start/end date1/09/0931/08/13

Funding

  • EPSRC: £134,180.00