Full disk 4.3 μm spectra at R = 3000 for three disk models with different inner CO₂ abundances. The outer ¹²CO₂ abundance is 10^-7 with g/d_gas = 1000. Thin lines show the emission from ¹²CO₂, thick lines the emission from ¹³CO₂. For both isotopes individual line peaks can be seen but the lines blend together in the wings forming a single band. Spectra are shifted vertically for display purposes.