In a new study performed at the Center for Nanoscale Materials at the U.S. Department of Energy (DOE)’s Argonne National Laboratory, researchers have, for the first time, seen the self-assembly of nanoparticle chains in situ, that is, in place as it occurs in real time.
The scientists exposed a tiny liquid “cell” or pouch that contained gold nanoparticles covered with a positively charged coating to an intense beam of electrons generated with a transmission electron microscope. Some of the electrons that penetrated the outside of the cell became trapped in the fluid medium in the cell. These “hydrated” electrons attracted the positively charged nanoparticles, which in time reduced the intensity of charge of the positive coating.
As the hydrated electrons reduced the coating's positive charge, the nanoparticles no longer repelled each other as strongly. Instead, their newfound relative attraction led the nanoparticles to “jump around” and eventually stick together in long chains. This self-assembly of nanoparticle chains had been detected before in different studies, but this technique allowed researchers, for the first time, to observe the phenomenon as it occurred.
To read more, click here.