Mapping and controlling nucleation

从溶液中成核新相，例如晶体的成核，对工业和基础科学都具有极其重要的意义。在过去350年里，工业结晶几乎没有什么变化，令人尴尬的是缺乏控制，有时会出现意想不到的严重财务后果。不幸的是，自一个世纪前Ostwald和Gibbs的工作以来，对晶体成核的理论理解并没有太大的进步。例外的是Cölfen关于非经典成核理论的工作和Frenkel关于临界密度波动在结晶过程中的作用的工作。然而，这些新的想法经常应用在化学工程中，而不是真正了解潜在的化学物理的适用性。在这里，建议绘制和控制液体中成核的早期阶段。成核将以其最一般的形式处理，即液-气、液-液和液-固，同时考虑液-液临界点的可能存在。将这些系统驱离平衡非常远，将允许我们创建亚稳态和不稳定态，这将导致成核和旋节分解。随后的高度非平衡过程将使用透射光和拉曼显微镜，特别是使用一系列对环境敏感的荧光团的荧光显微镜来绘制。我们建议开发一种新的仪器，它将改变晶体成核的研究，并将朝着控制结晶的多晶型迈出第一步。它包括使用强大的皮秒和飞秒激光诱导成核，以及可编程的衍射光学，导致大规模平行成核装置。将使用先前开发的测绘技术实时跟踪所产生的成核事件。这一突破将使我们能够进行大量的实验，并首次收集有意义的统计数据。大规模平行成核仪将用于进行一系列成核控制实验，从相对直接的液晶相或气泡成核，到利用光的自旋和轨道角动量的“大规模平行光学搅拌器豆”诱导成核中的手性。

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.