Fig. 2

SIMS data from residues of irradiated phosphine-doped ices. The spectra were recorded in the negative (top) and positive ion mode (bottom) correlated with the formation of 18O-substituted oxoacids formed in irradiated phosphine (PH3)–water (H218O) (right) and phosphine (PH3)–carbon dioxide (C18O2) (left) ices