Departure coefficients b, for the selected levels of the investigated atoms as a function of log τ₅₀₀₀ in the model atmosphere 5811/4.0/−4.5. Bottom panel: we show every fifth of the first 60 levels for Fe i. They are quoted in the bottom-right part of the panel. All remaining higher levels of Fe i are plotted by dotted curves. We show the same for Fe ii. They are quoted in the top-right part of the panel. S_H = 0.1 throughout.