Abundances in the PIR (with respect to total gas number density) for the 200 km s^-1 shock model. Top: ions and atoms. Bottom: molecules. Abundances in the pre-shock gas are those derived from Sect. 4.1.2 at 3000 days post-explosion and for a density increase x = 200. They are plotted as symbols at t = 0 (blue circle: O₂; black cross CO; pink square: SiS; red triangle: SiO). The SiO pre-shock abundance value is 1 × 10^-17.