The RT-TDDFT methodology described previously was used to probe the dissociation of PFOA/PFOS with a variety of optical fields. For clarity, we only discuss the dissociation dynamics of PFOA in the main text, and the results for PFOS (which are similar) are described in the Supporting Information. To choose a relevant excitation energy (ω), we first computed the absorption spectrum of PFOA + 43 H2O molecules (depicted in Fig. (a)) using a standard RT-TDDFT procedure described in our previous work. Specifically, the Kohn-Sham orbitals for these optical absorption calculations were propagated for 25 fs with a time step of 8 as, and a 0.23 eV full-width-at-half-maximum Gaussian broadening was used to plot the spectrum. The optical absorption spectrum in Fig. (b) shows a near continuum of excitations beyond the optical gap of ~5 eV, which indicates that the system does not strongly absorb below 5 eV. As such, we set the excitation frequency (ω) of the optical pulse to 6 eV for all our photo-induced studies. Fig. ) depicts the temporal dependence of the electric field of the optical pulse used in our calculations.