Radiation damages living cells.This is mainly due to the attack on genes by unstable and highly reactive OH radicals (OH molecules with unpaired electrons) that are generated by ionizing water that occupies most of the cells by irradiation to generate electrons. It is considered.

　Since the rate at which OH radicals diffuse in water and cause a chemical reaction is relatively slow, there are various research examples.However, there are many unclear points because the electron motion is very fast.It is said that electrons lose energy while moving in water, and are finally captured as bubble-like hydrated electrons in the gaps between water molecules.When these hydrated electrons eventually adhere to molecules in an aqueous solution, a reduction chemical reaction occurs, but the reactivity depends on the energy of the hydrated electrons.Therefore, it is important to know the electron energy accurately for the elucidation of radiation chemistry.

　This time, the joint research group conducted an experiment called time-resolved photoelectron spectroscopy, in which two laser beams are applied to liquid water to observe electron motion in the molecule with a time lag.Succeeded in accurately determining the energy of hydrated electrons by detailed theoretical analysis.As a result, it was found that the energy of hydrated electrons, which was previously considered to be 2 electron volts, is 3.3 electron volts, which is more stable than the conventional estimation.

　In the future, it will be necessary to clarify whether high-energy electrons generated by radiation are attached to molecules and cause a reduction reaction before they are relaxed to become stable hydrated electrons.In addition, although it is difficult to accurately calculate the electronic states in water with the current capabilities of computers, we would like to work on theoretical calculations in the future.

Paper information:[Science Advances] Genuine binding energy of the hydrated electron