Top panel: VUV (120−340 nm) photoabsorption spectra of pure CO₂ ices deposited at 75 K before and after (solid black and blue lines, respectively) 1 keV electron irradiation with a total fluence of 2.2 × 10¹⁷ e⁻ cm⁻² (i.e., a dose of 9.9 × 10² eV/16u). A VUV spectrum of pure CO ice is also displayed (solid green line). Bottom panel: VUV (120− 340 nm) photoabsorption spectra of pure H₂O ices deposited at 80 K before and after (solid black and red lines, respectively) 1 keV electron irradiation with a maximum total fluence as for pure CO₂ ice. The VUV photoabsorption spectrum of the processed ice heated to 140 K is also shown (solid green line).