Emission-line luminosities from best-fit slab models (integrated between 12 and 16 μm) vs. peak-to-continuum values from the slab models and fit to the continuum, with marker styles indicating the spatially resolved submillimeter structures in Table 2. Targets in the upper-right quadrant show the clearest molecular gas detections, and we report nondetections (red markers) when peak-to-continuum ratios are <0.03 or emission-line luminosities are smaller than ﹩\mathrm{log}L\lt -5.1\,{L}_{\odot }﹩ (black, dashed lines). While disks with resolved submillimeter dust cavities show C₂H₂ and HCN emission lines, none of these sources have CO₂ emission.