Preface

Understanding the size and shape dependence of physical properties in nanoscale particles is a fundamental step towards the design, the fabrication, and the assembly of materials and devices with predictable behavior. In recent years, there has been a remarkable advancement in the ability to fabricate shape-controlled nanoparticles, for example rods, wires, and nanoparticles with branched shapes, especially via synthetic approaches in solution. Shape-controlled inorganic nanoparticles are among the most promising candidates as building blocks in nanoscale materials and devices, both because their physical properties are modified considerably compared to those of spherical nanoparticles and because their intrinsic geometry opens many new opportunities for their assembly into organized super-structures. In this book, we have decided to review the physical properties of elongated inorganic nanoparticles, with particular emphasis on the transition in these properties when the shape of the nanoparticles evolves from a sphere to a rod, but we will consider in many cases also nanowires. From the point of view of specific properties and materials, we have decided to cover the optical properties of semiconductors and noble metals, the electrical properties of semiconductors, the magnetic properties of various metals and metal oxides, the catalytic properties of various classes of materials, and the mechanical properties of metals and metal alloys. Chapter 1 will give an introduction into some basic quantum physics concepts, specifically tailored to the following Chaps. 2 and 3 that are devoted to the optical and electrical properties of semiconductor nanorods. Semiconductor nanocrystals are among the most studied materials in nanoscience nowadays, due to the large number of potential applications employing these materials, for example, in optical devices (lasers [1–3], light emitting diodes [4, 5], photo-detectors [6], solar cells [7–9]), or biological labeling [10, 11], to cite a few. Elongated, rod-shaped semiconductor nanocrystals possess interesting physical properties which depend on their size, aspect ratio, and chemical composition, and these nanoparticles have been proposed as active materials in light emitting devices [12], photocatalysis [13], optically induced light modulation [14], photovoltaics, [7–9, 15] wavefunction engineering [16–18], and optical memory elements exploiting the exciton