Left panel: C¹⁸O₂ ice experimental column densities for ion irradiation experiment (beam of ⁵⁸Ni¹¹⁺ at 46 MeV) discussed in Seperuelo Duarte et al. (2009). Middle panel: −dN∕dF calculated from the recorded data. The blue circles represent the data used in the fit, whereas the sky blue points are discarded as they represent the phase transition of the ice observed at the early irradiation stage (low fluence). The long, dashed orange line corresponds to the best-fit models using Eq. (1), and the dashed orange line to what would be expected from thick film behaviour. The dotted green line represents the fit using previously determined values from Seperuelo Duarte et al. (2009). Right panel: sputtering yield evolution and fitted contribution as a function of column density.