Lab-grown crystals that explode in light

Chemistry students at the University of Cincinnati (UC) are exploring lab-grown crystals that do extraordinary things when exposed to light.

They bend. They twist. They bounce. And sometimes they explode.

Prof. Anna Gudmundsdottir is studying photo-explosive crystals in her lab. The topic hasn’t received much attention from researchers, so her students are on the frontiers of discovery with every new and surprising reaction they observe.

“We’re studying what makes crystals behave when exposed to light. We can make them jump, explode, or dance. They do all kinds of weird things,” Gudmundsdottir says.

She received a $550,000 grant from the National Science Foundation to examine the properties of crystals UC students grow in the chemistry lab. They react to light in different ways depending on the way the molecules are packed inside them.

“It fascinates me that the same molecules can create different crystals,” UC doctoral student Fiona Wasson says.

When irradiated with light, some crystals bend at either end with the strength to lift objects hundreds of times their size. Others twist into a helix of more than 360°. Others almost hop off the microscope slide like tiny jumping beans.

Gudmundsdottir says the light prompts the crystals to expel atmospheric nitrogen trapped when the crystals form, adding, “We’re the first ones to experiment with the gas release, so the discovery makes it a lot of fun for the students.”

For his undergraduate research fellowship, UC student Ben Miller spent a semester in a lab darkroom Gudmundsdottir built for documenting photo-explosive reactions in crystals.

Students use adjustable red lights to focus a microscope’s cameras on the tiny crystals before hitting them with a variety of LED lights.

Miller learned the crystals bending from light can also be manipulated with mechanical force using tiny needles and tweezers. Experimenting with them was a lot of fun, he says.

“What’s cool about one of these crystals is it bends, and when it snaps back, there’s no damage to the surface,” Miller says.

Typically, crystals UC students grow in the lab only put on a show once before their nitrogen escapes. But other crystals can bend or twist repeatedly, raising the possibility of creating light-powered sensor actuators.

Gudmundsdottir sees more potential for light-activated crystals that release oxygen. These could be used to create a safer, lightweight oxygen system for airplanes suffering a loss of cabin pressure at altitude.

Or even someday for exploring space, where light is abundant. “It’s exciting to study this. We’re just in the first few years of exploring it,” Wasson says.

University of Cincinnati
https://www.uc.edu