Same as Fig. 7 but including the other models considered for the ice and core composition. Shown from the top left to the lower right are: silicate core, M50 ice mantle composition and size distribution τ₃, a_max = 3µm (model #13); silicates and amorphous carbon core, M15 ice composition, and size distribution τ₃, a_max = 3 µm (model #16); silicate core, M15 ice mantle composition, including pure CO and size distribution τ₃, a_max = 3 µm (model #19); and silicate core, MX ice mantle composition, including H₂O, CO₂, CO, and NH₃, and size distribution τ₃, a_max = 3 µm (model #22). The inserts display close-ups of the CO₂ ice band (and CO for models #19,22), with spectra normalised at 4.1 µm (4.55 µm for models #19,22).