Femtosecond x-rays solve contentious question of how azobenzene flips between isomers

Firing femtosecond x-ray pulses at azobenzene has helped chemists study how its structure changes as it flips between isomers in solution, finding that a twisting of the carbon–nitrogen bond initiates the reaction.¹ The researchers behind the work say that this is the first time that their technique has been used on molecules with only light atoms. The team also suggests that their technique could be used to study other fast, light-driven reactions.