Online assessment of the crystalline modification of nanoparticles in the gas phase

从气相中合成纳米颗粒是一种资源高效且常见的方法。由于因果关系的研究，人们知道颗粒的性质(大小、形态、团聚程度、结晶度)可以通过改变工艺参数来改变。目前，合成粒子的性质在样品提取和制备后离线表征，具有相当大的时延，因此只产生关于过程到产品事件链的稀缺信息，不允许对其产生直接影响。在DFG/AIF联合项目的第二个资助阶段--利用创新的在线测量系统(MPAC)对基于颗粒的功能材料进行多参数表征--因此，将开发一种在线和现场测量方法，用于分析气相中颗粒的结晶度，并在一个新的子项目中进行测试。结晶度作为颗粒的内部结构参数，与活性物质的生物利用度或颗粒的导电性等应用手段有很大的相关性。有了这个项目，迄今为止尚未涵盖的参数结晶度方面的工作补充了其他MPAC子项目的形态、尺寸和结构的分析工作。本项目的目的是开发一种新的拉曼测量方法，用于在线和现场评估纳米颗粒在气相中的结晶修饰，并同时分析气相温度和组成。这使得可以研究不同的工艺参数对相应的气相颗粒工艺中所得到的产品性质的影响。借助拉曼光谱，可以根据气溶胶的特征光谱特征来区分气溶胶中的多晶型。同时，利用氮气的转动拉曼光谱确定了气相温度。由于与同时发生的光-物质相互作用相比，拉曼散射的截面相对较弱，因此特别注意有效地激发和检测拉曼信号，同时最小化并发和干扰信号(化学发光、荧光)。这将通过优化和建立专门为该项目定制的光谱仪和应用移位激发拉曼差分光谱(SERDS)方法来实现。该测量方法将基于分散在气相中的二氧化钛、二氧化锆和氧化铁(III)颗粒体系来开发。

The synthesis of nanoparticles from the gas phase is resource-efficient and common. Thanks to cause and effect studies, it is known that particle properties (size, morphology, degree of agglomeration, crystallinity) can be changed by a variation of process parameters. Presently, the properties of the synthesized particles are characterized offline with considerable time delay after sample extraction and preparation, thus yielding only scarce information about the process-to-product event chain and not allowing direct influence on it. Within the second funding phase of the DFG/AIF joint project - Multi parameter characterization of particle based functional materials by means of innovative online measurement systems (MPaC) - , hereby an online and in-situ method of measurement for the analysis of the CRYSTALLINITY of particles in the gas phase is to be developed and tested in a new sub-project. The crystallinity as an internal structural parameter of particles has enormous relevance for the means of application, such as the bioavailability of active agents or the conductivity of particles. With this project, the hitherto not covered aspect of the parameter CRYSTALLINITY complements the works for the analysis of morphology, size and structure of the other MPaC sub-projects. Aim of this project is the development of a new Raman measurement process for the online and in-situ assessment of the crystalline modification of nanoparticles in the gas phase, with the simultaneous analysis of the gas phase temperature and composition. This allows investigating into the influence of varied process parameters on the resulting product properties in corresponding gas phase particle processes. By means of Raman spectroscopy, it is possible to distinguish polymorphs in aerosols by their characteristic spectral signatures. Simultaneously the gas phase temperature is ascertained from the rotational Raman spectrum of nitrogen. Due to the relatively weak cross-section of Raman scattering compared to concurring light-matter interactions, particular attention is paid to the efficient excitation and detection of the Raman signals, at the same time minimizing concurring and interfering disturbing signals (chemiluminescence, fluorescence). This will be realized by optimizing and building up a custom-made spectrometer especially for this project, and the application of the Shifted Excitation Raman Difference Spectroscopy (SERDS) method. The measurement method will be developed on the basis of the particle systems Titanium dioxide, Zirconium dioxide, and Iron(III) oxide dispersed in the gas phase.