Experimental evidence pertaining to the structure of the hydrated electron is reviewed. In agreement with recent picosecond optoelectronic data, it is concluded that at low or moderate temperatures the hydrated electron is not an electron at all! Rather, it is very likely a hydrated semi-ionic pair (OH...H30)(aq), having the chemical properties of either OH-(aq) or H(aq). However, under certain conditions, where the hydrogen-bond structure of the solvent is weak, the hydrated electron may delocalize somewhat into the surrounding water medium.to become "its old self", behaving more like an electron in a cavity. This fragmented personality of one of chemistry's most celebrated fundamental particles is further substantiated by ab initio quantum mechanical calculations.
G. W. Robinson,
H. F. Hameka,
"The Hydrated Electron -- Jekyll And Hyde In A Test Tube", Proc. SPIE 0742, Laser Applications to Chemical Dynamics, (1 January 1987); doi: 10.1117/12.966908; https://doi.org/10.1117/12.966908