Laser, camera, action: Ultrafast ring opening of thiophenone tracked by time-resolved XUV photoelectron spectroscopy

Light-induced ring opening reactions form the basis of important biological processes such as vitamin D synthesis, and are also touted as promising candidates for the development of molecular switches. In recent years, new time-resolved techniques have emerged to investigate these processes with unprecedented temporal and spatial resolution.

An international research team from the USA, UK, Germany, Sweden, Australia, and the local team at the FERMI free-electron laser, combined time-resolved photoelectron spectroscopy with high-level electronic structure and molecular dynamics calculations to unravel the dynamics of a prototypical reaction along the full photochemical cycle of a ring molecule (thiophenone) – from photoexcitation, ring opening, all the way through to the subsequent ground state dynamics, and spanning a range of tens of femtoseconds  to hundreds of picoseconds. “These processes have intrigued the photochemistry community for decades” says Prof. Daniel Rolles from Kansas State University “and it is now routinely possible to visualize electronic changes and the movement of atoms in the molecule at each step of a chemical reaction”.

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Image: Artistic rendering of the photo-induced ring opening of thiophenone (left) into several open-ring products (right). The thin white lines show smoothed paths of actual trajectories. Illustration: KSU, Daniel Roles.