VUV (120−340 nm) spectra of pure CO₂ ices deposited at 20 K before and after (solid black and red lines, respectively) 1 keV electron irradiation with a total fluence of 2.2 × 10¹⁷ e⁻ cm⁻², i.e., a dose of9.9 × 10² eV/16u. A step size interval of 0.05 nm is used to resolve the fine structures in the spectral range between 120 and 160 nm. The reminder of the VUV spectra are acquired with a step size of 1 nm. A VUV spectrum of pure CO ice acquired with a step size of 0.1 nm is also displayed for comparison (solid green line).