Time‑resolved X‑ray liquidography maps azobenzene photo‑switch in solution

Researchers have captured the step‑by‑step motion of azobenzene molecules as they switch shape under light, using time‑resolved X‑ray liquidography. The method tackles a long‑standing problem in physical chemistry: watching how atoms move and interact inside a crowded liquid. Kim et al. applied the technique to the textbook light‑induced isomerisation of azobenzene dissolved in a solvent. Their measurements reveal precise details of the photo‑isomerisation pathway, showing how the molecule’s nitrogen‑nitrogen double bond rotates and how the surrounding solvent cages respond. The study also proves that time‑resolved X‑ray liquidography can follow low‑mass atoms, such as hydrogen, even when they are buried in a bulky solvent matrix. By delivering snapshots on the femtosecond to picosecond timescale, the approach provides a direct view of the transient structures that drive the reaction. The work builds on earlier scattering and spectroscopy studies and demonstrates a new route for probing fast chemical changes in realistic liquid environments. ## Context The technique offers a way to film molecular transformations in conditions that resemble real‑world solutions, helping chemists link observed reaction rates to the underlying atomic motions.