ABSTRACT
One of the main driving forces for the research of nanoscale materials is the size dependence of their physical properties.1 Consequently, many applications take advantage of these phenomena, as has been described in several contributions throughout this book. On the other hand, this strong size dependence will necessarily hamper a detailed investigation of nanostructures, because the preparation of, e.g., nanocrystals does not lead to particles that are absolutely identical. Even though several synthesis methods have been developed to prepare very different kinds of nanocrystals with size distributions of only several percent, the particles are still slightly different in diameter, shape, surface structure, and crystallinity.2-4 As a consequence, the physical properties will be slightly different among the particles within an ensemble. However, the development of devices from nanoparticles depends strongly on the understanding of their individual properties and, therefore, the investigation of single particles is a precondition for the buildup of nanocrystals assemblies and the understanding of their collective behavior.
