Analytical Ultracentrifuge

分析性超离心（AUC）是一种胶体分析方法，可以对分散体系进行完整的表征。分散在溶剂中的纳米粒子或大分子在离心场中分离，而吸收或干涉光学允许在样品细胞中观察这一过程。数据评价分别从沉积边界速度和扩展得到沉积和扩散系数及其分布。从这些参数和测量，颗粒大小，形状以及分子量和样品密度是可访问的。相互作用的系统也可以通过AUC进行分析；沉积-扩散-平衡实验得到了化学计量学和化学平衡常数。AUC是一种绝对方法。由于对整个系统进行了分馏和光学检测，得到了具有较高统计意义的数据。事实上，AUC是一种高分辨率技术，可以解决Ångström范围内颗粒大小的差异。利用现代瑞利干涉光学，可以分析极稀色散和浓色散。光吸收样品可以使用多波长吸收（MWA）探测器进行表征，这可以识别复杂混合物中的不同成分。在金属和半导体纳米颗粒的情况下，MWA探测器允许详细表征尺寸相关的光学特性（分别由于等离子体共振和量子尺寸效应）。在这个项目中，分析式超离心机将被用来解决各种问题。一方面，它将用于研究从溶液形成固体的早期阶段，即表征最小的簇、核和中间体，以及它们与添加剂（从简单分子到蛋白质）的相互作用。另一方面，该装置将用于回答半导体纳米结构、多功能两亲体、多孔有机-无机固体、复杂纳米粒子和纳米粒子超结构以及合成聚合物等领域的各种问题，为生物材料的使用量身定制。所要求的设备对于固体形成的早期阶段的分析是必不可少的，并且将至关重要地有助于回答上述化学材料科学领域的各种问题。

Analytical Ultracentrifugation (AUC) is a method of colloid analytics, which enables a complete characterization of dispersed systems. Nanoparticles or macromolecules, dispersed in a solvent, are separated in a centrifugal field, while absorption or interference optics allow observing this process in the sample cell. The data evaluation yields the sedimentation and diffusion coefficients, and their distributions, from the sedimenting boundary velocity and broadening, respectively. From these parameters and measurements, particle size, shape as well as molecular weight and sample density are accessible. Interacting systems can also be analyzed by means of AUC; sedimentation-diffusion-equilibrium experiments yield the stoichiometry and equilibrium constant of chemical equilibria.AUC is an absolute method. Due to the fractionation and optical detection of the entire system, data with high statistical significance are obtained. Indeed, AUC is a high-resolution technique, which can resolve differences between particle sizes in the Ångström range. Using modern Rayleigh interference optics, both very dilute and concentrated dispersions can be analyzed. Light absorbing samples can be characterized using multiwavelength absorbance (MWA) detectors, which allows identifying distinct components in complex mixtures. In case of metal and semiconductor nanoparticles, the MWA detector allows characterizing size dependent optical properties (due to plasmon resonance and quantum size effects, respectively) in detail.In this project, the Analytical Ultracentrifuge will be used to address various questions. On one hand, it will serve to study the early stages of the formation of solids from solution, i.e., to characterize smallest clusters, nuclei and intermediates, as well as their interactions with additives, ranging from simple molecules to proteins. On the other hand, the device will be used to answer various questions in the areas of semiconductor nanostructures, multifunctional amphiphiles, porous organic-inorganic solids, complex nanoparticles and nanoparticle superstructures, as well as synthetic polymers, tailor-made for the use in biomaterials. The requested device is literally indispensable for the analyses of the early stages of the formation of solids, and will crucially contribute to answering various questions in the above mentioned fields of chemical materials science.