Ultra Small Surface Force Measurements in Vacuum

对纳米尺度上的粘合剂相互作用的深刻理解对于各种应用是重要的，例如对于在微米和纳米组装期间处理颗粒和构建块，用于工业清洁过程和医疗药物输送。基于原子力显微镜的力谱与胶体探针技术和其他力测量工具，在理解基本的粘合剂相互作用方面取得了巨大进展，在这一领域的理论思考。然而，环境大气中的力谱总是只产生货车范德华力、静电和毛细效应的叠加。此外，胶体探针的研究与颗粒直径小于1微米是罕见的，由于有限的能力，以制造这样的小探针没有一个复杂的湿化学过程和限制的几何形状和材料选择。在水介质中的测量减少了毛细作用力，但同时它们可以引入新的作用力并改变化学环境。此外，在环境或水介质中获得的数据并不完全适用于扫描电子显微镜内部的处理过程，因为它们没有考虑电子束和真空环境的影响，而扫描电子显微镜已经成为纳米操纵和纳米组装的首选环境。直接研究货车范德华力和静电相互作用，而不受毛细管力的影响，也不需要含水介质，并在扫描电子显微镜内探索电子束诱导效应对粘附力和静摩擦力的影响。此外，常见的粘附理论和近似值将在通常由毛细相互作用和跳跃接触效应叠加的力范围内进行验证。为了实现这一目标，一个专用的力谱设置超过目前的力分辨率限制将结合高分辨率扫描电子显微镜/聚焦离子束仪器。通过这种方式，在扫描电子显微镜的真空室内采用定制的基板和胶体探针与迄今为止无法实现的各种尺寸，几何形状和材料的系统粘附力研究将是可行的，从而允许更深入地了解毛细管力和粘合剂的相互作用一般，并为新的微米和纳米处理策略让路。

Profound understanding of adhesive interactions on the nanoscale is important for a variety of applications as for example for handling of particles and building blocks during micro- and nanoassembly, for industrial cleaning processes and for medical drug delivery.Atomic force microscope based force spectroscopy with the colloidal probe technique and other force measurement tools have led to great advances in the understanding of fundamental adhesive interactions and verified theoretical considerations in this field. However, force spectroscopy in ambient atmosphere always yields only a superposition of van der Waals, electrostatic and capillary effects. Moreover, colloidal probe studies with particles below 1 micrometer in diameter are rare due to the limited ability to fabricate such small probes without a complicated wet-chemical process and restrictions regarding geometry and material selection. Measurements in an aqueous medium reduce the capillary forces, but at the same time they can introduce new force contributions and alter the chemical environment. Furthermore, data gained in ambient or an aqueous medium is not fully applicable to handling processes inside the scanning electron microscope, which has become a preferred environment for nanomanipulation and nanoassembly, as they do not take into account the influence of the electron beam and the vacuum environment.This project aims at two main objectives: directly investigating the van der Waals and electrostatic interactions without the influence of capillary forces and the need for an aqueous medium, and exploring the influence of electron beam induced effects on adhesion and stiction inside a scanning electron microscope. Furthermore, the common adhesion theories and approximations will be validated in the force range that is normally superimposed by capillary interaction and jump to contact effects. To achieve this goals a dedicated force spectroscopy setup surpassing the current force resolution limits will be combined with a high resolution scanning electron microscope/focused ion beam instrument. In this way, systematic adhesion force studies inside the vacuum chamber of the scanning electron microscope employing tailored substrates and colloidal probes with hitherto unachievable variety regarding size, geometry, and material will be feasible, thus allowing for deeper understanding of capillary forces and adhesive interactions in general, and making way for new micro- and nanohandling strategies.