Optical trapping and manipulation has flourished at the sub-nanometre scale, where light-matter mechanical coupling has enabled cooling of neutral atoms, ions and molecules, and at the micrometre scale, where the momentum transfer associated with the scattering of light allowed the manipulation of microscopic particles and biological entities. However, it has been difficult to scale either of these techniques to the nanoscale, a size range of crucial importance for a wealth of potential appli- cations based on technologically significant nanomaterials, such as quantum dots, nanowires, nanotubes, graphene and two-dimensional crystals, as shown in Fig. 23.1. Only recently several novel approaches have been suggested and realised to overcome such difficulties. In this Chapter, we review the state of the art in trapping and manipulation of nanostructures with an emphasis on some of the most promis- ing advances in controlled manipulation and assembly of individual and multiple nanostructures.
23.1 Metal nanoparticles
23.2 Semiconductor nanostructures
23.3 Optical force lithography and placement
23.4 Prospects for nanotweezers
23.5 Further reading