Interestingly, similar reshaping processes were observed to occur in the absence of silver precursor during LP-TEM and white light irradiation (Figure , Supporting Movie 6). Here, sharpening of the AuNR tips and corners occurred concurrently with roughening of the sides due to the development of pitted regions during growth (Figure ). Forcherio et al. observed similar pitted AuNRs after Pt photodeposition with no sacrificial hole scavenger. LP-TEM imaging showed growth of adjoining fins and smaller adjacent particles with continuous imaging, which are characteristic of growth under diffusion limited conditions or at elevated temperatures. The weaker dark-field contrast of the newly formed Au regions indicates thinner films in these areas compared to the original AuNR. Overall, the projected particle area increased in time with an accelerating growth rate (Figure ), unlike the constant growth rate observed in the presence of AgNO3 (Figure ). The increase in growth rate with time could result from an autocatalytic growth process where the increase in gold surface area with time accelerates the growth dynamics. White light illumination of AuNRs in solvent with no silver precursor displayed similar reshaping, albeit less dramatic morphological changes and no formation of dendritic surface layers (Figure ). During sample preparation there was no discernible reshaping of the AuNRs by halide or oxidized gold species or by the applied plasma treatment for ligand removal (see SI, Section 7). Given that we have established radiolysis is nearly absent in this solvent, the morphological changes of electron-or light-irradiated AuNRs in the absence of silver precursor could be due to plasmonic hot carrier-mediated etching, reduction, and redeposition of Au. IPA is a strong hydroxyl radical scavenger, leaving only plasmonically generated hot holes as the potential oxidizing species. Direct electron beam-AuNR interactions, such as sputtering or knock-on damage, do not significantly contribute because the threshold electron energy for these processes is larger than 200 keV. No re-shaping processes occurred for AuNRs in pure toluene (Supporting Movie 7), likely due to rapid recombination of hot holes and electrons in the absence of hole or electron scavengers. Prior work suggests that in addition to the widely known ability of IPA to scavenge OH • and H • radicals, IPA can also scavenge pre-solvated electrons with diffusion limited kinetics. Al-Zubeidi et al. proposed photoemitted hot electrons from plasmonic nanoparticles may inject into surrounding solution to form solvated electrons. As such, a fraction of generated hot electrons may be scavenged by IPA, leaving a net excess of hot holes unable to recombine with hot electrons. Asymmetry in plasmonic hot carrier scavenging rates by IPA may be exacerbated by factors including limited adsorption of IPA to highly polar gold surfaces, or short lifetimes of hot holes compared to hot electrons. Therefore, insufficiently rapid hot hole quenching can enable hot holes to etch Au 0 into gold ions. Formation of the irregular dendritic structures observed in LP-TEM may be due to slower diffusion rates within the LP-TEM liquid layer compared to bulk liquids, promoting Au redeposition near the AuNR surface by hot electrons. Overall, plasmonic hot carrier-driven Au etching and redeposition in the presence of 80:20 toluene:IPA is consistent with both in situ LP-TEM and ex situ observations and is potentially due to imbalanced hot carrier scavenging rates by IPA. We performed finite difference time domain (FDTD) simulations to determine whether the trends uncovered in Figure and resulting AuNR morphologies after LP-TEM imaging could be rationalized by electron beam-induced plasmonic effects (Figure ). The 3D simulations accounted for salient conditions of the LP-TEM studies, such as the solvent, electron beam fluxes, the silicon nitride substrate, and STEM probe movement (See details provided in SI, Section 8).