First-principles simulation of an ejected electron produced by monochromatic deposition energy to water at the femtosecond order

Kai, Takeshi   ; Toigawa, Tomohiro   ; Matsuya, Yusuke  ; Hirata, Yuho   ; Tezuka, Tomoya*; Tsuchida, Hidetsugu*; Yokoya, Akinari*

Although scientific knowledge of photolysis and radiolysis of water is widely used in the life sciences and other fields, the formation mechanism of the spatial distribution of hydrated electrons (spur) resulting from energy deposition to water is still not well understood. The chemical reaction times of hydrated electrons, OH radicals, and HO in the spur strongly depend on the spur radius. In our previous study, we elucidated the mechanism at a specific given energy (12.4 eV) by first-principles calculations. In the present study, we performed first-principles calculations of the spur radius at the deposition energies of 11-19 eV. The calculated spur radius is 3-10 nm, which is consistent with the experimental prediction (~4 nm) for the energy range of 8-12.4 eV, and the spur radius gradually increases with increasing energy. The spur radius is a new scientific knowledge and is expected to be widely used for estimating radiation DNA damage.