Aliphatic C-H destruction cross section σ_d obtained with the exponential fit as a function of the electronic cross section S_e for the different ion/energy irradiation of our a-C:H (filled dots for a-C:H 1, and squares for a-C:H 2) and soot (black asterisks) samples. Cross sections calculated from data of different a-C:H irradiation studies are represented with blue diamonds (Adel et al. 1989; Baptista et al. 2004; Baumann et al. 1987; Fujimoto et al. 1988; González-Hernández et al. 1988; Ingram & McCormick 1988; Marée et al. 1996; Mennella et al. 2003; Pawlak et al. 1997; Prawer et al. 1987; Som et al. 2005, 1999; Zou et al. 1988). See text for details.