Optical Control of Intermolecular Forces

使用激光来操纵小颗粒和细胞/通常被称为“光学镊子”/是一种成熟的研究工具。它日益突出，在不同的实验室中找到了应用。镊子方法通常是通过施加一个力，将粒子吸引到高强度区域，通常是激光束的中心。这种机制，以及其他用于激光冷却和捕获原子的机制，都利用了直接作用于单个物质粒子的力。最近，一项完全不同的发现引发了一波激动人心的浪潮：在纳米尺度上，在粒子之间运行的光诱导力。这种粒子间力提供了许多非常独特的特征，可以用来对物质进行受控的光学操纵。通过这种相互作用，已经在理论和实验上证明了创造光学有序物质的新机会，导致了最近文献中引入的术语，如光学结合和光学物质。尽管决定正常物理和化学行为的力的起源应归因于单个分子的内在属性，但这些光诱导力的运作方式非常不同，最好的是，它们是实验可控的。这是一个现在正在以极快的速度发展的科学领域，其巨大的潜力最早是在15年前发表的一篇关于化学未来的有影响力的论文中预测的。去年，申请者和东英吉利大学的同事开发了一个关于光学诱导的粒子间作用力的综合理论，确定了一些以前没有确定的影响，并表明根据给定的条件，这种作用力可以是吸引的，也可以是排斥的。根据新理论对各种系统进行了计算，确定并说明了应用范围。关于碳纳米管的第一个结果表明了光学改变纳米管薄膜结构的可能性，而随后的应用发现了光学图案化和聚集的新形式。现在，人们建议将理论应用于更复杂的系统，为创新的技术应用铺平道路。第一项任务将是构建这些粒子间力如何在包括原子团、胶体和液晶在内的各种系统中运行的详细表示；还将检查光学有序微阵列的形成和稳定性。接下来集中于表面和近表面效应，寻求光学改变表面吸附、表面上的分子相互作用和悬浮中纳米颗粒的光学有序性的方法。充分描述这种效应应该会开启重大的材料应用。还将注意粒子被与结构光相关的复杂光场照射时所预期的特殊效果，例如被称为“光学涡旋”的奇异激光光束。其他感兴趣的系统是由激光束之间的干涉引起的对图案化光场的光学机械响应。已经证明，全息方法可以同时捕获和引导数百个悬浮粒子，但光学结合在这种应用中的具体作用还没有被研究，这一调查的结果将被热切地等待。其他要研究的问题是光学修饰表面处理的可能性，以及薄膜生产的过程。

The use of laser light to manipulate small particles and cells / commonly known as 'optical tweezers' / is a well established research tool. It is increasingly prominent, finding applications in diverse laboratories. Tweezer methods generally operate by exerting a force that attracts particles to regions of high intensity, usually the centre of the laser beam. This mechanism, and others that are employed in laser cooling and trapping of atoms, utilise forces that operate directly on individual particles of matter. Recently a wave of excitement has been created by a discovery of something quite different: optically induced forces that operate between particles, over nanoscale dimensions. Such inter-particle forces offer a number of highly distinctive features which can be exploited for the controlled optical manipulation of matter. Through such interactions, new opportunities for creating optically ordered matter have already been demonstrated both theoretically and experimentally, leading to the introduction of terms such as 'optical binding' and 'optical matter' in recent literature. Whereas the forces that determine normal physical and chemical behaviour owe their origin to the intrinsic properties of individual molecules, these optically induced forces operate very differently / and best of all, they are experimentally controllable. This is an area of science that is now advancing with extreme rapidity, its enormous potential having been first predicted in an influential paper on the future of chemistry, published fifteen years ago. Last year the applicant and co-workers at the University of East Anglia developed a comprehensive theory of optically induced inter-particle forces, identifying a number of effects not previously determined, and showing that such forces can be either attractive or repulsive according to given conditions. Calculations based on the new theory were performed for a variety of systems, identifying and illustrating the scope for applications. The first results on carbon nanotubes indicated possibilities for optically modifying the structure of nanotube films, while subsequent applications identified new forms of optical patterning and clustering. Now it is proposed to develop theory for application to more complex systems, to pave the way for innovative technical applications. The first task will be to construct a detailed representation of how these inter-particle forces operate within a variety of systems including atomic clusters, colloids and liquid crystals; the formation and stability of optically ordered microarrays will also be examined. Focusing next on surface and near-surface effects, methods are to be sought for optically modifying the character of surface adsorption, molecular interactions on surfaces, and the optical ordering of nanoparticles in suspension. Fully characterising such effects should unlock significant materials applications. Attention will also be given to the special effects anticipated when particles are irradiated by the complex optical fields associated with structured light, such as the exotic laser beams known as 'optical vortices'. Other systems of interest are the optomechanical response to the patterned light field that results from the interference between laser beams. It has been shown that holographic methods can simultaneously trap and steer hundreds of suspended particles, yet the detailed role of optical binding in such applications has not yet been studied; the results of this investigation will be keenly awaited. Other issues to be examined are the possibility of optically modifying surface treatments, and processes of thin film production.