A bit of stray moisture during an experiment tipped off scientists about the strange behavior of a complex oxide material they were studying — shedding light on its potential for improving chemical sensors, computing and information storage.

In the presence of dissociated water molecules on its surface, the layered material emits ultraviolet light from its interior. The researchers — who hail from Drexel, the University of Pennsylvania, the University of California at Berkeley, and Temple University — discovered they could control UV light production via a chemical reaction that functions like flipping a light switch.

“This discovery is quite remarkable because we uncovered a chemical reaction at the surface that prompts the emission of light from the interface within,” says Drexel’s Jonathan Spanier, “and we are able to turn it off and on again. Amazingly, we can also make it stronger by increasing the distance between the molecules and surface and the buried interface, by using thicker films, for example.”

Their findings appeared in the American Chemical Society journal Nano Letters.