Results from CASINO simulations of 1 keV electrons trajectories in N- and O-rich ices. For each simulation 1000 trajectories were calculated. All electrons impinging normal to the O₂ ice surface are stopped at 0.045 μm (blue line), while only about 50, 70, and 90% of electrons are stopped in solid N₂ (red line), nitrogen oxides (light and dark green and light blue lines) and the O₂:N₂ = 1:1 ice mixture (black line) at this depth.