Near-surface processes of beam-sensitive materials under low energy electron irradiation

• Carbon nanopillars form on AuCl 3 under low-energy e-beam irradiation. • C-pillar width decreases while height increases with accelerating voltage. • Void and Au nanoparticle formation observed in crystal subsurface. • Voids linked to energy deposition, not thermal effects, during electron bombardment. • Near-surface E-beam alteration affects EDS accuracy in beam-sensitive materials. We investigate the interactions and modifications induced by low-energy electron beam irradiation in beam-sensitive materials, with crystalline gold trichloride (AuCl 3 ) as a model system. Employing scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS) in an operando setup, we investigated surface and bulk transformations as a function of irradiation time (0–1080 s) and accelerating voltage (1–30 keV). Irreversible structural changes were observed both on the surface and within the bulk of the AuCl 3 crystal. Surface analysis revealed the formation and growth of µm-sized vertically oriented carbon nanopillars, with voltage-dependent growth dynamics governed by backscattered (BSE) and secondary electrons (SE). At the same time, the bulk of the AuCl 3 decomposed under carbon pillars, forming Au nanoparticles and near-surface voids whose size and spatial distribution correlated with the energy deposition profiles. The observed morphological and chemical alterations pose a significant obstacle to accurate chemical composition analyses by energy-dispersive X-ray spectroscopy (EDS) and suggest a narrow operating window for conducting reliable SEM analysis