Argonne and other institutions report first-ever atomic freeze frame of liquid water

By: Argonne National Laboratory via Business Wire

February 16, 2024 at 09:00 AM EST

In an experiment akin to stop-motion photography, scientists have isolated the energetic movement of electrons while “freezing” the motion of the much heavier atoms it orbits in liquid water. The new technique involved opens up a whole new field of experimental physics and could benefit future studies of radiation-induced processes such as encountered in space travel, cancer treatments, nuclear reactors and legacy waste.

Their study, recently published in the journal Science, built on the new science of attosecond physics, recognized with the 2023 Nobel Prize in Physics. An attosecond is a billionth of a billionth of a second. For scale, there are more attoseconds in a second than there have been seconds in the history of the universe. The study sample was a stream of liquid water, chosen as a model molecule in this first-ever experiment.

“Until now radiation chemists could only resolve events at the picosecond timescale, a million times slower than an attosecond,” said Linda Young, a senior author of the research, Distinguished Fellow at the U.S. Department of Energy’s Argonne National Laboratory and professor in the Department of Physics and James Franck Institute at the University of Chicago. “It’s kind of like saying ‘I was born and then I died.’ You’d like to know what happens in between. That’s what we are now able to do.”

For the study, the research team used a new technique, called all X-ray attosecond transient absorption spectroscopy. This allowed them to take a fingerprint of the electronic response following ionization in liquid water, all before the bulkier hydrogen atoms have time to move.

The findings demonstrate that a longstanding measurement of the structure of liquid water has been misinterpreted. The new technique reveals the instantaneous electronic changes when matter is hit with an X-ray, an important step in understanding the effects of radiation exposure on objects and people.

This was a multi-institutional effort that no one institution could have accomplished in isolation. Participants include Argonne National Laboratory, Center for Free-Electron Laser Science at the Deutsches Elektronen-Synchrotron, Hamburg Centre for Ultrafast Imaging, Pacific Northwest National Laboratory, SLAC National Accelerator Laboratory, Universität Hamburg, University of Chicago, University of Washington and Washington State University.