Normalized integrated intensity profiles of the CH⁺ v = 1–0 P(5) line, ${\mathrm{C}\mathrm{H}}_3^{+}$ emission between 7.16 and 7.20 μm, H₂ 0–0 S(1) line, H₂ 0–0 S(9) line, and AIB emission at 3.3 and 3.4 μm (Left) across the protoplanetary disk d203-506 (Right) and across the dissociation fronts as a function of the distance to the star θ¹ Ori C. The position of the cut through d203-506 is presented in Peeters et al. (2024). In the Bar, each point corresponds to the intensity averaged on apertures with width of 2′′ and height varying from 0.2′′ to 1.5′′ to increase the S/N. The maps used to derive the intensity profile of H₂ lines (resp. ${\mathrm{C}\mathrm{H}}_3^{+}$ emission) are presented in Zannese & Sidhu (in prep) (resp. Berné et al. 2023). The line 0–0 S(9) was chosen as its wavelength is close to the wavelength range of CH⁺ infrared rovibrational emission, so the comparison between the lines is less affected by extinction. CH⁺ and ${\mathrm{C}\mathrm{H}}_3^{+}$ emission follows better the emission of excited ${\mathrm{H}}_2^{\ast }$ than the emission of less excited H₂ and the emission of AIBs.