Colloidal Monolayers in Periodic Laser Fields

周期性激光场中的胶体单分子层

• 批准号: 459399860
• 负责人: Professor Dr. Stefan U. Egelhaaf (†)
• 金额: --
• 依托单位: Institut für Theoretische Physik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/459399860?language=en
• 关键词: Colloidal; Monolayers; Periodic; Laser; Fields

Soft matter systems are frequently encountered in everyday life. Many cleaning and cosmetic products, glue, nappies, food stuff as well as natural and biological materials are considered soft matter. The main characteristic of soft matter is its susceptibility to external perturbations, such as mechanical, electrical or magnetic forces. Thus, soft matter systems are soft, as suggested by their name.Within this project we investigate the response of a colloidal system to an external potential. Colloidal systems are part of soft matter and consist of particles with a size between a few nanometres and a few micrometres that are dispersed in a medium. We use spherical particles that are arranged in one layer and thus represent a quasi-two-dimensional system. They are exposed to a sinusoidal light pattern that imposes a periodic potential on the particles, where the wavelength of the potential is of the order of the particle size. Exposing colloidal particles to a sinusoidal potential appears as a very fundamental situation. Surprisingly, however, theoretical models describing this situation are rare. Even very basic questions, like the particle arrangement and dynamics in such a potential, have been virtually untouched. To make progress, we combine experiments, simulations and theory. A theoretical model will be developed and its predictions compared with simulation and experimental results. The experiments furthermore are used to guide and inspire the development of the theoretical description.Optical microscopy will be used to follow the particles. This will yield systematic and quantitative information down to the level of individual particles and hence allow us to determine any parameter that is derived theoretically. Different theoretical approaches will be applied, including density-functional theory, integral-equation theory and mode-coupling theory. We aim at a determination of the arrangement and dynamics of particles exposed to a sinusoidal potential. The arrangement will be quantified in terms of density profiles and structure factors, while the dynamics will be characterized by the mean-square displacement, diffusion coefficient and intermediate scattering function. This information will also be used to construct the glass-transition lines in the state diagram. We anticipate a non-monotonic behaviour of the particle arrangement and dynamics as the periodicity and amplitude of the potential is varied.By studying colloidal particles exposed to a modulated potential, we push matter to extreme states. This allows us on one hand to probe material properties and gain a deeper understanding of the underlying processes and on the other hand to prepare and characterize materials with new properties.

软物质系统在日常生活中经常遇到。许多清洁和化妆品，胶水，尿布，食品以及天然和生物材料被认为是软物质。软物质的主要特征是它对外部扰动的敏感性，例如机械力、电力或磁力。因此，软物质系统是软的，正如它们的名字所暗示的。在这个项目中，我们研究了胶体系统对外部电势的响应。胶体系统是软物质的一部分，由分散在介质中的尺寸在几纳米到几微米之间的颗粒组成。我们使用球形粒子，它们排列在一层中，因此代表一个准二维系统。它们暴露于正弦光图案，该正弦光图案在颗粒上施加周期性电势，其中电势的波长是颗粒尺寸的量级。将胶体颗粒暴露于正弦电势似乎是一种非常基本的情况。然而，令人惊讶的是，描述这种情况的理论模型很少。即使是非常基本的问题，如粒子的排列和动力学在这样的潜力，几乎没有触及。为了取得进展，我们结合联合收割机实验，模拟和理论。将开发理论模型，并将其预测与模拟和实验结果进行比较。实验还被用来指导和启发理论描述的发展。光学显微镜将被用来跟踪颗粒。这将产生系统的和定量的信息，直到单个粒子的水平，从而使我们能够确定任何理论推导的参数。不同的理论方法将被应用，包括密度泛函理论，积分方程理论和模式耦合理论。我们的目的是在一个确定的安排和动态的颗粒暴露于正弦电位。该安排将被量化的密度分布和结构因素，而动态的特点是均方位移，扩散系数和中间散射函数。这一信息也将被用来构建状态图中的玻璃化转变线。我们预期粒子的排列和动力学的非单调行为的周期性和振幅的潜力是变化的。通过研究胶体粒子暴露于调制电位，我们推动物质的极端状态。这使我们一方面能够探测材料特性并更深入地了解底层过程，另一方面能够制备和表征具有新特性的材料。