Atomic motion captured in 4-D for the first time

Everyday transitions from one state of matter to another—such as freezing, melting or evaporation—start with a process called “nucleation,” in which tiny clusters of atoms or molecules (called “nuclei”) begin to coalesce. Nucleation plays a critical role in circumstances as diverse as the formation of clouds and the onset of neurodegenerative disease.

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Atomic nucleation textbooks will now have to be re written.

Tau.Neutrino said:

Atomic nucleation textbooks will now have to be re written.

And there are a lot of such books. I’ve read a couple. I had to when I was studying how sea salt aerosols act as nuclei for cloud droplet formation.

“The results were surprising, as they contradict the classical theory of nucleation. That theory holds that nuclei are perfectly round. In the study, by contrast, nuclei formed irregular shapes. The theory also suggests that nuclei have a sharp boundary. Instead, the researchers observed that each nucleus contained a core of atoms that had changed to the new, ordered phase, but that the arrangement became more and more jumbled closer to the surface of the nucleus.

“Classical nucleation theory also states that once a nucleus reaches a specific size, it only grows larger from there. But the process seems to be far more complicated than that: In addition to growing, nuclei in the study shrunk, divided and merged; some dissolved completely.

“Nucleation is basically an unsolved problem in many fields. Once you can image something, you can start to think about how to control it.”

Excellent work all round.