Just like the SOMO, the particle NTOs for the 533 eV transitions (see Fig. ter σ * OH orbitals. This antibonding character is directly responsible for the intensity of the 533 eV XAS feature, since σ * OH orbitals are admixtures of the 4a1 and 2b2 orbitals that underlie the pre-edge and main-edge features of water's XAS. Without mixing in this dipole-allowed character, a hypothetical O1s to pure-cavity transition would effectively produce a charge-transfer state with negligible oscillator strength. Furthermore, as Fig. shows, the energy of the 533 eV transition is largely dictated by the distance between the excess electron and first-solvation shell water molecules. The agreement between the theoretical and experimental XAS, both in terms of the energy of the 533 eV peak and its intensity, is therefore direct evidence of antibonding orbital occupation by e - (aq) . Because these are two independent observables, we do not believe the agreement between theory and experiment is fortuitous.