Model of a strongly irradiated and constant-pressure PDR with P_th = 2 × 10⁸ K cm⁻³ and G₀ = 2 × 10⁴, appropriate to the most irradiated layers of the Orion Bar PDR. Fractional abundances of SH⁺, H₂ (total), H₂ (v = 2), S⁺, S and, H are shown as a function of depth into the cloud. We also show f_H2, the fraction of H₂ that is in vibrationally excited levels v ≥ 2, and the gas temperature (in gray, right axis scale). The dashed SH⁺ abundance profile is for a model that uses the old formation and destruction rates (Zanchet et al. 2013a).