Gold Pyramids

[Recusant]

As I read this story, I thought to myself, "Simply amazing. That these scientists were able to observe this intriguing phenomenon, and that some institution was willing to lay out a significant pile of spondulics for them to discover it." Turns out, there are probably practical applications.

"Clusters of gold atoms form peculiar pyramidal shape" | EurekAlert!

A model of 20 oranges is compared with the theoretical and experimental structure.
Image Credit: KU Leuven

Clusters composed of a few atoms tend to be spherical. They are usually organized in shells of atoms around a central atom. This is the case for many elements, but not for gold! Experiments and advanced computations have shown that freestanding clusters of twenty gold atoms take on a pyramidal shape. They have a triangular ground plane made up of ten neatly arranged atoms, with additional triangles of six and three atoms, topped by a single atom [see figure where a model of twenty oranges is compared with the theoretical and experimental structure].

The remarkable tetrahedral structure has now been imaged for the first time with a scanning tunnelling microscope. This high-tech microscope can visualise single atoms. It operates at extremely low temperatures (269 degrees below zero) and uses quantum tunnelling of an electrical current from a sharp scanning metallic tip through the cluster and into the support. Quantum tunnelling is a process where electrical current flows between two conductors without any physical contact between them.

The researchers used intense plasmas in a complex vacuum chamber setup to sputter gold atoms from a macroscopic piece of gold. "Part of the sputtered atoms grow together to small particles of a few up to a few tens of atoms, due to a process comparable with condensation of water molecules to droplets," says Zhe Li, the main author of the paper, currently at the Harbin Institute of Technology, Shenzhen. "We selected a beam of clusters consisting of exactly twenty gold atoms. We landed these species with one of the triangular facets onto a substrate covered with a very thin layer of kitchen salt (NaCl), precisely three atom layers thick."

[. . .]

The new discovery helps scientists evaluate the catalytic and optical performances of these clusters, which is relevant for designing cluster-based catalyst and optical devices. Recent applications of clusters include utilisation in fuel cells and carbon capture.

[Link to full article.]

[xSilverPhinx]

That is cool

I'm hoping Hermes will say that silver takes the shape of a rose or something equally intricate, but I'm guessing it's highly unlikely.

[hermes2015]

That is cool

I'm hoping Hermes will say that silver takes the shape of a rose or something equally intricate, but I'm guessing it's highly unlikely.

No, not unlikely. We have living, walking proof in your own dear self. 

[Magdalena]

That is cool

I'm hoping Hermes will say that silver takes the shape of a rose or something equally intricate, but I'm guessing it's highly unlikely.

No, not unlikely. We have living, walking proof in your own dear self. 

Awwwwww.

[xSilverPhinx]

That is cool

I'm hoping Hermes will say that silver takes the shape of a rose or something equally intricate, but I'm guessing it's highly unlikely.

No, not unlikely. We have living, walking proof in your own dear self. 

Such a sweet talker you  

[hermes2015]

That is cool

I'm hoping Hermes will say that silver takes the shape of a rose or something equally intricate, but I'm guessing it's highly unlikely.

No, not unlikely. We have living, walking proof in your own dear self. 

Such a sweet talker you  

[Dark Lightning]

Sometimes I regret not going into materials science. I find this sort of thing fascinating.

[No one]

Hey you, this post is a treasure. On a scale of 1-200, I give it a 196.96657.

[Ecurb Noselrub]

Makes me what to play billiards with 20 gold balls (on the table, that is).

[Dark Lightning]

Hey you, this post is a treasure. On a scale of 1-200, I give it a 196.96657.