|Fabio Novelli, Martina Havenith and Claudius Hoberg (from left) were able to observe the birth of an electron dissolved in water in RESOLV. |
Photo Credit: © RUB, Marquard
With a new experiment, the effects of an electron in solution on the surrounding liquid have been observed.
So-called hydrated electrons play a major role in many physical, chemical and biological processes. They are not bound to an atom or molecule and are freely in the solution. Since they are only ever produced as an intermediate product, they are extremely short-lived. The team of the Ruhr Explores Solvation Cluster of Excellence RESOLV at the Ruhr University Bochum, a new experiment was the first time to observe how the hydrated electron acts on the solution over its life. The researchers around Prof. Dr. Martina Havenith-Newen report in the journal Proceedings of the National Academy of Science PNAS from 15. February 2023.
The simplest anion
"A single electron in water is the simplest conceivable anion, which, however, plays a major role in a large number of chemical processes," Martina Havenith describes the importance of the object of investigation. “For example, it plays an important role in energy transmission during photochemical and electrochemical phenomena, in atmospheric chemistry, in the radiation damage to biological substances and in medical therapy." For several decades, this has given the hydrated electron the constant attention of experimental and theoretical groups.
The researchers at RESOLV have set up a new experiment to follow the formation and temporal development of the hydrated electron from the solvent perspective: "We were able to observe a delocalized electron immediately after it was created using an intensive laser beam in a water jet," says Martina Havenith -Newen. The charge distribution extends over 20 angstroms. Within less than a millionth of a millionth of a second (500 femtoseconds), the cargo is localized in the water network in a ten times smaller area.
An astonishingly stable so-called localized electron is formed, the fingerprint of which in the water network was the first time that researchers were able to observe live due to the sensitivity of the experiment with an ultra-short laser pulse in the terahertz range. “The astonishing result was that the water envelope around the negatively charged electron is not as stable as, for example, in the case of salts, but the water molecules in the first shell can move even more than in normal water. "This smallest anion therefore plays a special role,” summarizes Martina Havenith-Newen.
"In addition, our recordings showed the formation of a water quake or a tsunami in the water," said Martina Havenith-Newen. The team was able to show that in parallel with the separation of the electron and the generation of a hydronium cation, waves are generated in the water network that only decay very slowly. "This became possible because with our new technology we can track even the smallest changes in the water network with a high time resolution," explains the researcher.
Published in journal: Proceedings of the National Academy of Sciences
Source/Credit: Ruhr University Bochum
Reference Number: chm021623_02