Diffusion energies vs. desorption energies obtained for O and N atoms (blue and green bands, respectively) on ASW ice, and O atoms (grey band) obtained on oxidized graphite. Dotted lines represent E_dif/E_des = 0.5, 0.7, and 0.9. Open symbols represent previous estimations of E_des for O atoms: 1350 K calculated by Bergeron et al. (2008) on pyrene; 1455 K found Ward & Price (2011) on C₂H₂-coated graphite; 1840 K measured by Kimber et al. (2014) on propyne ice; 1764 K found by He et al. (2014) on amorphous silicate; 1660 K and 1850 K measured by He et al. (2015) on porous water ice and amorphous silicate, respectively.