Probing the dynamics and structure of soft matter and out-of-equilibrium materials using 3D-photon correlation spectroscopy

这项提议的目的是建立一个最先进的所谓的3D光子相关光散射光谱（3D- pcs）设施，这是英国独有的，将供英国研究界使用。利用光散射来研究材料构建块的运动和结构是了解材料的有力方法。然而，为了利用光来研究一种材料，这种材料通常需要对光具有高度的透明度。不幸的是，大多数材料不是透明的，而是表现出不同程度的光学浑浊。如果一个人试图用光散射来研究这种浑浊的材料，结果通常是非常困难的，甚至不可能解释。然而，被称为3d光子相关光谱学的特殊光散射技术通过使用一个技巧来解决这个问题。一般来说，当使用光来研究一种材料时，激光束聚焦在你感兴趣的材料上，光被散射，你检测散射光的某个特定散射角度。通过分析散射光的时变强度，你可以计算出样品中负责散射的单元是如何移动的，通过研究散射光的时间平均强度是如何随散射角变化的，你可以计算出散射单元是如何排列的或它们有什么形状。如上所述，如果样品浑浊，问题就来了。这意味着光在离开样品之前通常会被散射很多次，关于散射事件的信息会丢失。3D-PCS技术中使用的技巧是，将入射光束分成两束，这两束中的每一束都聚焦在相同的样本量中。在这里，它们都经历了散射，通过同时分析这两个散射事件，我们可以发现那些散射事件，光在体积内只散射一次，因此在解释方面不会留下混乱。因此，这种强大的光散射技术对于研究许多凝胶、乳剂、生物材料等浑浊材料非常有用。事实上，在很长的时间和长度范围内，理解构建块的运动和结构是很重要的，但在光学上不清晰的材料是如此普遍，以至于物理学、化学、生物学、医学、工程等领域的研究人员都对获得这种技术感兴趣。此外，由于工业相关材料可能比大学实验室中使用的更“纯净”的材料更容易混浊，因此应用这项技术研究与工业产品相关的材料，如塑料、药品、个人护理产品或用于药物输送或电池的先进材料的兴趣是巨大的。

The aim of this proposal is to set up a state-of-the art so called 3D photon correlation light scattering spectroscopy (3D-PCS) facility, unique to the UK, that will be accessible the UK research community. The use of light scattering to study both the motions and structure of material building blocks is a powerful way to learn about materials. However, in order to investigate a material using light the material normally needs to be highly transparent to light. Unfortunately, most materials are not transparent, but show various degrees of optical turbidity. If one attempts to study such a turbid material using light scattering, the result is normally very difficult or even impossible to interprete. However, the particular light scattering technique termed 3D-photon correlation spectroscopy gets around this problem by using a trick. Generally, when studying a material by the use of light, a laser beam is focused upon your material of interest, light is scattered and you detect the scattered light for some particular scattering angle. By analyzing the time-varying intensity of the scattered light you can work out how the units within your samples that are responsible for the scattering move and by studying how the time-averaged intensity of scattered light varies with the scattering angle you can work out how the scattering units are arranged or what shape they have. The problem comes, as mentioned above, if the sample is turbid. This means that light is generally scattered many times before it exits the sample and the information about the scattering event gets lost. The trick utilized in the 3D-PCS technique, is that the incoming beam is divided into two and each of these two beams is focused into the same sample volume. Here, they both undergo scattering and by analyzing both these scattering events simultaneously, one can find those scattering events where light was only scattered once within the volume and thus no confusion will remain in terms of interpretation. This powerful light scattering technique is thus excellent for studying turbid materials such as many gels, emulsions, biological materials. In fact, materials where it is important to understand the motions and structure of the building blocks over a wide range of time- and length-scales, but where the materials are not optically clear are so common that researchers within physics, chemistry, biology, medicine, engineering etc are interested in having access to this technique. Moreover, since industrially relevant materials are perhaps even more likely to be turbid than the more 'purified' materials used in university labs, the interest in applying this technology to study materials relevant for industrial products such as plastics, pharmaceuticals, personal care products, or advanced materials for drug delivery or batteries is huge.