Imaging electron rearrangements in highly excited molecules
The molecule SF₆ undergoes Auger-Meitner decay (left), whereby multiple core electrons are ejected from a molecule, leading to large-scale rearrangement of the electronic structure of the molecule. The experiment tracks these changes using x-ray scattering, with a simulated detector image shown on the right.
Researchers have used ultrafast X-ray pulses to capture how electrons rearrange in highly excited molecules, offering a new way to observe the earliest stages of molecular change.
The study, published today in Nature Physics, examined sulfur hexafluoride molecules undergoing Auger–Meitner decay, a process in which an inner-shell electron is removed and the remaining electrons rapidly rearrange before the molecule breaks apart.
The research was conducted by a team from the University of Oxford, Brown University, the University of Tübingen and SLAC National Accelerator Laboratory using ultrafast hard X-ray pulses at the Linac Coherent Light Source in California.
By combining advanced X-ray scattering measurements with detailed theoretical modelling, the researchers showed that X-rays can reveal not only a molecule’s structure, but also how pairs of electrons redistribute in real space over extremely short timescales.
Researchers Mats Simmermacher, Adam Kirrander, and Andrés Moreno Carrascosa (L-R).
The work builds on a long-standing collaboration between Professor Peter Weber at Brown University and Professor Adam Kirrander at the University of Oxford, dating back to 2012. Early-career researchers also made major contributions to the study, including co-first authors Mats Simmermacher and Nathan Goff.
Professor Kirrander said:
“It is exciting to be able to resolve electron dynamics in such detail. This is the result of a great collaboration, with important contributions from the young scientists on the team.”
The result points towards a new generation of experiments in which increasingly short X-ray pulses could allow scientists to follow electronic motion ‘frame by frame’, shedding light on the earliest stages of chemical change, radiation damage and other ultrafast processes across chemistry, physics and biology.
