Fig. 1. Energy diagram of photoionization.

The ground-state hydrated electron e_aq⁻ is ionized by the ionization laser hν. E_sca is the energy loss due to scattering, eKE is the recorded electron kinetic energy, and eBE^(g) is the genuine electron binding energy (Eq. 2). V₀ is the location of the conduction band edge of water relative to the vacuum level (“escape barrier”).