Nanoparticles are at the forefront of many emerging technologies. These particles can often be designed with certain properties and can be used to create elaborate nanoscale structures. There is a debate in the scientific community however about how they assemble into these larger structures. Some theories describe the nanoparticles as 'artificial atoms' that form molecular-type structures. Researchers at Berkeley Lab have recently performed an experiment that watched nanoparticles to see just what it is that they do.
To perform the experiment two important hurdles had to be overcome. One was finding a way to keep the nanoparticles in view of the microscope. The second was to keep the liquid from getting too viscous and preventing the nanoparticles from moving. These were both overcome by using capillary action to draw platinum and iron molecular precursors to a liquid cell, which was then sealed with an epoxy. The smaller cell kept the particles in view and the epoxy seal prevented the liquid from drying and thickening.
Using transmission electron microscopes, including the powerful Transmission Electron Aberration-corrected Microscope (TEAM) with half-angstrom resolution, the particles were watched for hours. Previous experiments only allowed for minutes of observations. The resulting data showed the nanoparticles shaking around a bit as they attach to each other. At first the linked particles are all twisted up but eventually they straighten out to nanorods. This evidence supports the theory that nanoparticles behave like artificial atoms during crystal growth, which is important to know for designing and creating complex nanomaterials in the future.