3D image reveals atomic dance moments before molecule explosion

Scientists at the European XFEL near Hamburg have, for the first time, directly observed the quantum zero-point motion—the intrinsic, smallest possible vibrations of atoms—in a complex molecule just moments before it exploded. Using ultrashort, high-intensity X-ray pulses to ionize a 2-iodopyridine molecule, the team caused it to shatter into charged fragments. By tracking these fragments with a reaction microscope called COLTRIMS, which captures particle trajectories on femtosecond timescales, researchers reconstructed a three-dimensional map of the molecule’s shape and internal atomic motion at the instant of breakup. The observed fragment directions revealed subtle distortions inconsistent with classical flat molecular geometry, indicating coordinated quantum trembling rather than random thermal vibrations. The experiment demonstrated that classical physics alone could not explain the data; only quantum mechanical models matched the observations, confirming the presence of coherent quantum fluctuations in the molecule’s structure. The researchers used statistical methods to reconstruct complete molecular geometries from partial fragment data, enabling a detailed