A translator gets distracted by every rustle in the hall, and a one-hour meeting stretches into two. Single molecules squeezed between two metal contacts behave much the same way: they constantly change their shape and seating, and this affects how current and heat pass through them.

In the new study, the researchers took a molecule made of several benzene rings linked like train cars and clamped it between gold electrodes. Using very fast measurements, they simultaneously tracked the current and how well the molecule converts a temperature difference into electricity (a property called the Seebeck coefficient). It turned out that the molecule often rearranges, like a person shifting in a chair, and this makes the Seebeck coefficient jump noticeably, even though the current stays almost the same.

This result matters for the future: if we want to harvest heat that is currently just dissipated and turn it into electricity using single molecules, we need to understand how the molecule fidgets at the contacts. Now we have a way to watch this in real time and, possibly, make molecular devices more stable.