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Videos show bonds in short-lived metal clusters

A new imaging technique could help chemists study bonding in ephemeral molecules

by Ariana Remmel
July 1, 2022 | A version of this story appeared in Volume 100, Issue 24


Credit: Kimihisa Yamamoto
Chemists tracked the movement of two gold atoms in real time, revealing brief moments when they formed a metal dimer.

Chemists are interested in studying the catalytic activity of nanoparticles composed of just a few transition-metal atoms. But many of these complexes assemble and dissipate too quickly to observe with existing imaging methods. So chemists Kimihisa Yamamoto and Takane Imaoka of the Tokyo Institute of Technology and their colleagues devised a technique to record metal atoms on the move with scanning transmission electron microscopy. The researchers developed a method to distinguish between elements on the basis of scattering intensity and to track the movements of individual atoms. Next, they deposited transition-metal atoms such as gold, silver, and copper on a graphene plate to observe their movements. Using their new imaging platform, the researchers recorded the interactions between nascent metal dimers and trimers. This allowed them to observe short-lived bonds between transition-metal atoms, including the formation of an Au-Ag-Cu trimer that dissociated after 3 s (Nat. Commun. 2022, DOI: 10.1038/s41467-022-30533-y). Yamamoto says the team’s new imaging system could help researchers better understand the dynamic structural changes that underly metal cluster chemistry. “Regardless of whether the atoms are stable enough to form a bulk compound or not, the presence of a [molecule] can be recorded,” he says.

A time series of three panels labeled 1.8s, 2.3s, and 3.0s. Each image has three dots that represent a gold (yellow), silver (blue), and copper (red) atom clustered together.
Credit: Kimihisa Yamamoto
Using a new imaging technique, chemists filmed the few moments when three metal atoms—gold (yellow), silver (blue), and copper (red)—formed a bonded trimer.


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