Material specific on-line surface characterization of gas-borne particles

虽然颗粒的表面在很大程度上决定了它们的加工性能，如润湿性和凝聚力，但目前还没有原位技术可用于气态颗粒的表面表征。虽然电子光谱表面分析技术依赖于超高真空，但基于激光的方法复杂且昂贵，并且无法区分表面和体积性质。由于颗粒在润湿过程中也会发生结构变化，因此与尺寸相关的测量（如迁移率光谱法）也不适用。因此，拟议的研究项目旨在使用气溶胶光电子能谱和扩散充电相结合的气溶胶颗粒表面的原位表征。通过将光电发射信号与扩散充电信号相关联，与尺寸相关的效应（例如，重构）被抵消，并且仅测量表面性质。采用定义的冷凝实验的气体颗粒的润湿性可以在原位测量。最后，使用热扩散器，将通过施加温度斜坡来表征颗粒上的吸附物。

Although the surface of particles determines to a large extent their processing properties such as wettability and cohesion, there is currently no in situ technique available for the surface characterization of gas-borne particles. While electron spectroscopic surface analysis techniques rely on ultra high vacuum, laser based methods are elaborate and expensive and cannot distinguish between surface and volume properties. Since particles can also undergo structral changes during wetting, size related measurements such as mobility spectrometry are not applicable either. Therefore, the proposed research project aims at the in situ characterization of the surface of aerosol particles using a combination of aerosol photoemission spectroscopy and diffusion charging. By relating the photoemission signal to the diffusion charging signal size related effects such as restructuring cancel out and the mere surface properties are measured. Employing defined condensation experiments the wettability of the gasborne particles can be measured in situ. Finally, using a thermodenuder adsorbates on the particles will be characterized by applying temperature ramps.