Quantum confinement in low-dimensional semiconductor nanostructures enables materials with tuneable electronic and optical properties. This book discusses three-dimensionally confined structures in diamond, a material with remarkable physical attributes. Data for a series of size and shape-selected, hydrogen-passivated nanodiamonds (diamondoids) are presented. Diamondoids consist of face-fused cages that are perfectly sp -hybridized and thus directly superimposable on the bulk diamond crystal lattice. The present gas phase experiments provide benchmark data as they were obtained under...