Dumbbells and Detection Techniques...

Figure 1: Nano-objects with varying curvatures, Nature

ARGONNE, Ill. – Like snowflakes, nanoparticles come in a wide variety of shapes and sizes. The geometry of a nanoparticle is often as influential as its chemical makeup in determining how it behaves, from its catalytic properties to its potential as a semiconductor component. 

Thanks to a new study from the U.S. Department of Energy’s (DOE) Argonne National Laboratory, researchers are closer to understanding the process by which nanoparticles made of more than one material – called heterostructured nanoparticles – form. This process, known as heterogeneous nucleation, is the same mechanism by which beads of condensation form on a windowpane.

Heterostructured nanoparticles can be used as catalysts and in advanced energy conversion and storage systems. Typically, these nanoparticles are created from tiny “seeds” of one material, on top of which another material is grown. In this study, the Argonne researchers noticed that the differences in the atomic arrangements of the two materials have a big impact on the shape of the resulting nanoparticle. [1]

ARGONNE, Ill. ― A team of researchers from the U.S. Department of Energy's Argonne National Laboratory and Ohio University have devised a powerful technique that simultaneously resolves the chemical characterization and topography of nanoscale materials down to the height of a single atom.

The technique combines synchrotron X-rays (SX) and scanning tunneling microscopy (STM). In experiments, the researchers used SX as a probe and a nanofabricated smart tip of a STM as a detector.

Using this technique, researchers detected the chemical fingerprint of individual nickel clusters on a copper surface at a two-nanometer (nm) lateral resolution, and at the ultimate single atom height sensitivity. By varying the photon energy, the researchers used the difference in photoabsorption cross sections for nickel and the copper substrate to chemically image a single-nickel nanocluster - thus opening the door to new opportunities for chemical imaging of nanoscale materials. Until now, a spatial limit of about only 10-nm was attainable, and the researchers would simultaneously sample a large sample area. The researchers have improved the spatial resolution to 2 nm. [2]

Argonne National Laboratories:
1. Atomic 'mismatch' creates nano 'dumbbells', Jared Sagoff
2. Powerful new technique simultaneously determines nanomaterials' chemical makeup, topography, Angela Hardin