Andrew Barnum

An electron microscope scans a sample and records how electrons scatter off atoms at each point. The result is a giant stack of images — one for every point. These images encode information about how atoms are arranged: in neat rows or with a tilt, the orientation of the crystal lattice, and whether there are internal strains.

In a jeweler's workshop, gold is never mixed with ruthenium: one is soft and shiny, the other refractory and brittle. But at the nanometer scale, these metals merge into a single alloy that, when heated, begins to separate like oil and water in a cooling broth.

Hot gas settles on a substrate, building up a transparent film layer by layer. But instead of a perfect mirror, the surface sometimes gets covered with tiny bumps, like frost patterns on glass in severe cold. Usually, people try to remove them because they get in the way of making smooth components. Physicists from Oxford and their colleagues did the opposite: they looked inside the bumps.