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This study investigates the electron-stimulated desorption (ESD) of neutral D atoms from gibbsite and amorphous D2O ice using $2+1$ resonance-enhanced multiphoton ionization (REMPI) time-of-flight mass spectroscopy at varying temperatures. The findings reveal that while ESD yields are significantly reduced at cryogenic temperatures, amorphous D2O ice produces a substantially higher D atom signal compared to gibbsite, attributed to differences in surface density and bonding environments. This research elucidates the mechanisms of D atom production, highlighting the role of hole transport to terminal hydroxyl sites as a critical factor in nonthermal desorption processes, with implications for radioactive waste management.
Cooling gibbsite to 15 K slashes D atom yields by 50%, revealing the crucial role of hole mobility in desorption dynamics.
The electron-stimulated desorption (ESD) of neutral D atoms from gibbsite (\ce{Al(OD)3}) nanoplatelets and amorphous \ce{D2O} ice has been investigated using $2+1$ resonance-enhanced multiphoton ionization (REMPI) time-of-flight mass spectroscopy in a high vacuum chamber at temperatures 15 and 300\,K. Electron irradiation at 540, 250, and 150\,eV produces similar translational energy distributions at $\sim$300\,K, with a dominant intermediate-temperature component ($T \sim 1500$--$2100$\,K). Cooling to 15\,K suppresses the D atom yield by approximately 50\% and removes the lowest-temperature (slowest) component. This decrease in yield is consistent with diminished hole mobility and restricted diffusion at cryogenic temperatures. Under identical conditions, \ce{D2O} amorphous solid water ice films produce approximately 20 times greater D atom signal than bare gibbsite, with significantly hotter translational distributions, reflecting the higher deuterium surface density and distinct bonding environments of bulk ice relative to the terminal hydroxyl groups on gibbsite. These results identify hole transport to terminal hydroxyl sites as the rate-limiting step for nonthermal D atom production and provide a mechanistic framework for understanding atomic hydrogen release from aluminum hydroxide phases relevant to radioactive waste storage at the Hanford Site.