Infrared spectra of the HDO absorption band (top) and H₂O absorption bands (bottom) of a 6.18 × 10¹⁸ H₂O cm⁻² (2.17 μm) crystalline sample during irradiation with 10 keV electrons at 50 K, compared to an amorphous H₂O-ice sample of similar thickness grown at 50 K. The curves (from top to bottom in both panels, displaced vertically for clarity) correspond to fluences of 0, 0.95, 2.61, 6.95, 28.0, 101, 341, 510, and 1590 × 10¹⁴ electrons cm⁻². The bottom panel has been adapted from M. J. Loeffler et al. (2020).