The radius of gyration for an excess electron in solvated PFOA and PFOS (a total of 13 and 12 trajectories, respectively) is shown as a function of time in Figure in the Supporting Information. In particular, Figure shows that an excess electron in solvated PFOA exhibits qualitatively different dynamics than a true hydrated electron. Specifically, the excess electron trajectories are characterized with r g values decreasing rapidly to 1.25 Å in less than 100 fs (except for one trajectory, which decays to the same value after ∼0.60 ps). We also observed four trajectories with the same behavior in solvated PFOS in which r g initially fluctuates around 2.65 Å and decreases to its final value of 1.25 Å from ∼0.20 to ∼0.90 ps.