Three models that are representative of clouds in (1) the PHANGS sample (NGC 2903), (2) NGC 4038/9, and (3) NGC 3256. Left: Example n–PDFs from our model parameter space assuming α_PL = 3. Center: Temperature profiles of the example models. Right: Emissivity profiles of the example models. CO emissivity is shown as solid lines, and HCN emissivity is shown as dashed lines. The mass-weighted emissivity, ⟨ϵ_mol⟩, is given by Eq. (11). The range of densities over which radiative transfer is applied is slightly different between models, and depends on the average gas surface density of the model (see Sect. 2.3). We plot p_n over a wider range of volume densities (left plot) than those used when performing radiative transfer (center and right plots).