Nanoscopy

Understanding the property-function relation of nanoparticles in various application fields involves determining their physicochemical properties, which is still a remaining challenge to date. While a multitude of different characterization tools can be applied, these methods by themselves can only provide an incomplete picture. Therefore, novel analytical techniques are required, which can address both chemical functionality and provide structural information at the same time with high spatial resolution. This is possible by using tip-enhanced Raman spectroscopy (TERS) but due to its limited depth information TERS is usually restricted to investigations of the nanoparticle surface. Here, we establish TERS experiments on polystyrene nanoparticles after resin embedding and microtome slicing. With that, we gain unique access to their internal morphological features, and thus, enable to differentiate between information obtained for core- and shell-regions. Complementary information is obtained by means of Transmission Electron Microscopy (TEM) and from Force-Distance (FD) curve based Atomic Force Microscopy (AFM). This multimodal approach achieves a high degree of discrimination between resin and the polymers used for nanoparticle formulation. The high potential of TERS combined with advanced AFM spectroscopy tools to probe the mechanical properties is applied for quality control of the resin embedding procedure.