The physical non-reactive collisions with the nobel gases could be seen as being a dominant force in this formation mechanism. However, the atoms still needed to find each other and form chemical bonds to create the supramolecule that is the desired nanostructures. So in that sense, the chemical forces are the most important. A crystalline host can be used as a means of both isolating and ordering nanostructured arrays. CuCl crystallites have been prepared inside single crystals of NaCl and KCl.
Zeolites provide an excellent host for nanostructure formation.
The cages provide both the framework to isolate the structures from each other, and at the same time impose a long range order that can introduce new optical and electronic properties. Micelles and vesicles can also be useful hosts for generating nanocrystals. By using these molecules as the seeds, one can then carefully grow them from their sub-nanometer starting dimension to a few nanometers and maintain the narrow size distribution inherent in the molecular starting material. A rather clever variation on the reduction method employs either sample irradiation by g-rays or exposure to pulse radiolysis with high energy electrons from a van der Graff accelerator or similar device. When a solution containing metal cations is so exposed, the high energy particles impacts on the solvent water, producing a shower of solvated electrons along with numerous ions and radicals.