This is what an atom “swims” in liquid looks like

A small fathom on the atomic scale that could have profound implications for research.

For the first time ever, a team of researchers has managed to make a very impressive observation: they have tracked individual atoms as they move through a thin layer of liquid. Work that could quickly start to weigh heavily in fundamental research in physics and chemistry.

Even if this perspective made John Dalton and the other illustrious scientists who have worked on these objects throughout history salivate, the fact of observing an isolated atom is no longer exceptional in our time.

In a decade, for example, we have seen the flowering of very impressive works on this subject. We can cite this incredible photo of an individual atom, or the very first direct observation of atoms in motion in a raw material. On the other hand, reproducing this observation in a liquid is another matter.

An observation delayed by technical limits

The concern is that the few techniques that make it possible to make these observations work very poorly in this environment. Among the technologies that usually make it possible to observe individual atoms, there is in particular transmission electron microscopy (or TEM) and its derivatives. But unfortunately, this technique requires enclosing the object to be observed in a small vacuum chamber. The problem is that the properties of many materials change dramatically with pressure. Anything but ideal for studying their behavior…

And this technical limit leaves a considerable gray area in current physical models. This is particularly damaging for researchers, because understanding these interactions is crucial in a whole host of diverse and varied fields; mastering this dynamic would make it possible to make significant progress in fluid mechanics, in human physiology, in the operation of batteries… and so on.

Given the widespread importance of these behaviors in industry and science, it is very surprising that we still have so much to learn about the fundamentals of the interaction of atoms on a surface in contact with liquid. says Sarah Haigs, a materials science researcher at the University of Manchester.

With her colleagues, she therefore sought a way to observe this phenomenon in order to study its various implications. And they finally managed to achieve this based on the findings of several previous works.

The outer mesh represents the graphene “sandwich”, and the yellow clusters are the platinum atoms. © Kelly et al.

Atoms floating in a graphene sandwich

The first concept they reused was documented in a 2016 study. There, the researchers presented a concept of TEM capable of operating in a liquid or gaseous environment. But to achieve the required level of precision, this device is not enough on its own.

In a standard optical microscope, the object is traditionally trapped between two glass slides. Here, the team relied on a study that showed the potential of graphene lamellae. It is a perfect material in this case. It takes the form of a grid of carbon atoms that only measures than an atom thick. It is also resistant and fully inertwhich means that there can be no parasitic chemical reaction between the graphene and the object under study.

The researchers filled this nanometric sandwich with a saline solution where a few atoms of platinum. And their efforts were rewarded; using liquid-phase TEM, they were able to observe these atoms evolve in their tiny pool.

The other good news is that this new technique has already made it possible to draw some conclusions about the interaction between solids and liquids. In their press release, the authors explain that they have found that the liquid accelerates the movement of atoms and modifies their preferential anchoring points. And that’s just the beginning.

“This is a landmark achievement,” say the researchers. They are already looking to use this process to accelerate the development of environmentally friendly materials and industrial processes. In this case, it is the production of green hydrogen. But this is just one example among many for this technology which could have profound implications in many fields.

The text of the study is available here.

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