Ultrafast X-rays reveal how azobenzene switches shape

Using ultrafast X-ray pulses, researchers have for the first time tracked how the azobenzene molecule changes shape in the first picoseconds after absorbing light. The question had remained unresolved for nearly 50 years.

• Azobenzene switches between two forms when exposed to light
• X-ray pulses captured the molecule's motion within the first picoseconds
• The switching mechanism had puzzled scientists for nearly 50 years