Tsunami in a water glass

The simplest anion

"As the simplest anion, hydrated electrons represent a model system that is relevant in a multitude of radical chemical processes," says Martina Havenith-Newen, describing the importance of the study object. "For example, it plays an important role in energy transfer during photo- and electrochemical phenomena, in atmospheric chemistry, in radiation damage of biological substances and in medical therapy." This has earned the hydrated electron the ongoing attention of experimental and theoretical groups for several decades.

RESOLV researchers have set up a novel experiment to follow the formation and temporal evolution of the hydrated electron from the perspective of the solvent: "Immediately after its generation by means of an intense laser beam, we were able to observe a delocalised electron," Martina Havenith-Newen describes. The charge distribution extends over 20 angstroms. Within 500 femtoseconds, the charge is localised and a surprisingly stable localised electron emerges, whose fingerprint in the water network the researchers were able to observe for the first time due to the sensitivity of the experiment in the terahertz range.

"In addition, we could observe a water quake or a tsunami," says Martina Havenith-Newen. The team was able to demonstrate that this phenomenon is caused by the sudden charge separation during the formation of the hydrated electron. In contrast to atomic, negatively charged ions, the water network in the immediate vicinity is looser and not more stable. This means that the individual water molecules in the immediate vicinity of the electron can move more freely than in the water. "This smallest anion therefore takes on a special role," sums up Martina Havenith-Newen.