Results from CASINO simulations of 1 keV electrons trajectories in pure CO₂ and H₂O ices, in a CO₂:H₂O (6:1) ice mixture and in H₂CO₃ ice. For each simulation 1000 trajectories were calculated. All electrons impinging normal to the pure CO₂ and CO₂:H₂O (6:1) ice surfaces are stopped at 0.04 μm (solid blue and black lines, respectively), while all electrons are stopped in pure H₂O and H₂CO₃ ices at 0.06 μm (solid red and green lines, respectively).