Mapping and controlling nucleation

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The nucleation of a new phase from solution, such as the nucleation of crystals, is of immense importance to both industry and fundamental science. Industrial crystallisation has changed little in the past 350 years and suffers from an embarrassing lack of control with sometimes unexpected and severe financial consequences. Unfortunately, the theoretical understanding of crystal nucleation has not improved much since the work of Ostwald and Gibbs a century ago. Exceptions are the work by Cölfen on non-classical nucleation theories and that of Frenkel, on the role of critical density fluctuations in crystallisation. However, these new ideas are often applied within chemical engineering without a real understanding of the applicability of the underlying chemical physics.Here it is proposed to map and control the early stages of nucleation in liquids. Nucleation will be treated in its most general form, that is, liquid-gas, liquid-liquid, and liquid-solid, while taking into consideration the possible presence of liquid-liquid critical points. Driving these systems very far from equilibrium, will allow us to create meta- and unstable states that will give rise to nucleation and spinodal decomposition. The subsequent highly non-equilibrium processes will be mapped using transmitted-light and Raman microscopy and, in particular, fluorescence microscopy using a range of environmentally sensitive fluorophores. We propose to develop a novel instrument that will change the study of crystal nucleation and will make the first steps towards control over the polymorph that crystallises. It involves laser-induced nucleation using powerful picosecond and femtosecond lasers, and programmable diffractive optics, resulting in a massively parallel nucleation set-up. The resultant nucleation events will be followed in real-time using the mapping techniques developed previously. This breakthrough will allow us to carry out very large numbers of experiments and collect meaningful statistics for the first time. The massively parallel nucleation instrument will be used to carry out a number of nucleation-control experiments ranging from the relatively straightforward nucleation of liquid-crystalline phases or bubbles, to the induction of chirality in nucleation using "massively parallel optical stirrer beans" employing the spin and orbital angular momentum of light.