The polarization of the electric field is oriented perpendicular to the axis of the PFOA molecule. Finally, to further examine the polarization and subsequent dissociation dynamics of the C-F bonds in PFOA, we computed the Kohn-Sham orbitals as a function of time in Fig. . Since these orbitals are complex-valued (i.e., Eq. ( ) is a complex-valued integro-differential equation), we used the following visualization scheme in Fig. : the opacity denotes the magnitude of the complex-valued orbital, and its color (ranging from red to blue) represents its phase. At t = 0, the highest occupied molecular orbital (HOMO) is real-valued and almost entirely localized on nearby water molecules. As time progresses, the HOMO starts to delocalize onto the PFOA molecule during 8-16 fs, and some electronic charge transfers from the water to PFOA. This excess charge occupies the previously empty 3sF and 2pC atomic orbitals on PFOA, which possesses a strong σ* anti-bonding character. Once these empty orbitals become occupied, a dissociative electron attachment (DEA) process occurs: the subsequent electron-nuclei motion causes the C-F bond to elongate and destabilize (since the HOMO now has an anti-bonding character) until it irreversibly dissociates. This dynamic mechanism is reminiscent of the pseudo-Jahn-Teller effect that enables a charge density redistribution and produces highly directional ionic forces that destabilize specific bonds in chemical/material systems. Finally, the positively charged hole remaining in the solvent (which arises from a charge-transfer excitation) becomes stabilized by the surrounding water molecules thereafter. This general dissociation mechanism is also similar to that observed in highresolution gas-phase electron-collision experiments in which electron attachment to a CF4 molecule also leads to C-F bond dissociation. However, the major difference is that electrons in these prior experiments were artificially produced with an electron beam/gun, whereas the source of electrons in our solvated PFAS system naturally arises from nearby water molecules that are dynamically excited with an optical pulse. Finally, it is worth mentioning that our approach highlights the importance of utilizing these RT-TDDFT techniques for probing excited-state, photo-induced degradation of PFAS contaminants, which have started to garner immense attention in the scientific community.