The Fastest Reaction in Water
A collaboration including SSRL's Anders Nilsson, Dennis Nordlund and Hirohito Ogasawara have used high-intensity synchrotron x-rays to observe the fastest reaction ever before seen in watera reaction that takes a mere 3.6 femtoseconds.
This reaction is the first step of what happens when ionizing radiation meets water. The interaction starts when x-rays force an electron out of the core, or innermost, orbital around the oxygen atom’s nucleus. This leaves a hole in the core, which lasts a mere 3.6 femtoseconds before it is filled by another electron.
The rearrangement of the water molecule's electrons during the core hole's brief lifetime results in one of the hydrogen atoms migrating away from the oxygen. Once dissociated, the molecular fragments can perpetrate chemical reactions and cause serious damage in biological tissues and other materials.
Understanding how ionizing radiation interacts with matter has broad applicability to medical diagnosis and treatment, nuclear reactor operations, and much more.
Led by Clemens Heske of the University of Nevada, the experiment was done at the Advanced Light Source at Lawrence Berkeley National Laboratory, and Michael Odelius of Stockholm University performed the crucial theoretical simulations. More information from ALS News...
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