AuNRs were deposited onto silicon nitride LP-TEM chip windows by drop casting and drying, followed by ligand removal using oxygen plasma cleaning. Individual AuNRs were imaged in 0.25 mM silver nitrate dissolved in a solvent of 80:20 toluene:IPA (by volume) using continuous scanning TEM (STEM) at known electron flux (See the Supporting Information for detailed experimental methods (SI, Section 1)). Continuous imaging of the AuNRs did not form new metal particles in areas away from AuNR surfaces despite employing a moderate electron flux of 19.5 e - /(A 2 s), indicating that this solvent mixture suppressed radiolytic reduction of silver ions (Supporting Movie 1). In contrast, prior work has shown that similar electron fluxes applied to aqueous silver nitrate solutions caused rapid self-nucleation of nanoparticles and formation of faceted shells on AuNRs. Here we observed a gradual increase in the projected area and change in the AuNR shape over ~5 minutes (Figure ). The AuNR grew in both the longitudinal and transverse directions with progressive sharpening of tips and formation of protrusions at the rod side/rod end junctions (see Supporting Movie 1 for full data set). The nanorod aspect ratio decreased with time due to the faster relative width increase compared to the length increase (Figure ). The total projected area of the nanorod increased linearly with time (Figure ). The growth velocity of the AuNR surface varied as a function of position, with larger growth velocities observed at the rod side/rod end junctions (Figure ). The hot spots in the growth velocity spatial map agree with simulated hot electron generation and field enhancement hot spots from prior works. The particle growth trajectory here differed from in situ Ag deposition onto AuNRs in aqueous LP-TEM environments, which produced faceted shells or dumbbell deposition patterns. The final morphology and composition of the AuNRs after exposure to continuous STEM irradiation was qualitatively and quantitatively similar to that obtained by ex situ white light photodeposition experiments carried out on similarly prepared samples (Figure ). Here a cluster of three AuNRs in the silver precursor was irradiated at an electron flux of 12.5 e -/(Å 2 s) and observed with LP-TEM for nearly 8 minutes (Supporting Movie 2). Each AuNR formed sharp tips and protrusions at the rod end/rod side junction points (Figure ). Small particles were observed to self-nucleate in this case, which is thought to be due to accumulation of hydrogen gas in the sample after ~3 hours of imaging. While the small particles in solution could migrate and attach to AuNRs, the self-nucleated particles formed independent of the primary AuNR reshaping and silver surface deposition process (Supporting Movie 2). The liquid sample cell was disassembled and the same AuNRs were characterized with STEM energy dispersive X-ray spectroscopy (EDS) elemental mapping (Figure , Figure ). EDS elemental mapping showed silver signal across the particle surfaces extending beyond the edge of the gold signal by a few nm (Figure ). Ex situ photodeposition experiments illuminating AuNRs in the same precursor overnight with white light produced AuNRs with similar EDS signal and morphological features compared to the LP-TEM experiments (Figure , Figure ). Plasmonic photodeposition of Pd onto AuNRs was previously observed to produce particles with similarly narrowed tips. Additionally, the relative intensities of the Ag Kα and Au Lα signals in the EDS spectra were similar, producing integrated area ratios of approximately 0.36 and 0.17 respectively, indicating both conditions produced similar and elevated Ag:Au ratios due to Ag deposition (Figure ). In