|The image on display in this week's image of the month (new item) is brought to you by Bosch-Navarro & Rourke both from the University of Warwick. (DOI) What you see is a very organised gathering of 9 gold atoms on a carbon surface. And not by coincidence.|
For this TEM image to happen graphene oxide (GO) was treated with potassium thioacetate to generate GO covered with thiol groups (GOSH!) As the carbon material was also partially reduced it was expected to behave like graphene.
The gold cluster Au9(PPh3)8(NO3) was then selected. This particular molecule has one gold atom surrounded by 8 others. As GOSH was stirred with this gold compound in DMSO it attached itself by exchanging a surface sulfur atom for a phosphine ligand. GOSH@Au9 was then transferred from DMSO solution (simply by drying out) on so-called lacey carbon which is a carbon-copper supported grid designed for TEM.
The TEM images show discrete clusters with variations with respect to the surface. If the resolution was just a tiny bit higher all 9 individual atoms would be visible. The experimental configurations were backed up by TEM image simulations. In time-lapse mode the rotation of the gold wheel around it's sulfur attachment point can even be observed.