Figure 4. Portion of noncyclic (CO2)3 isomer nI band spectrum. The observed spectrum corresponds to a c-type band of an asymmetric top, with a hybrid character of <0.10. The model spectrum (Gaussian width 575 MHz, 0.87 c type, 0.13 a type) correctly reproduces the observed features, including the strong Q branch at 2343.3 cm-1. The gaps in the observed spectrum are due to CO2 monomer transitions ~including hot band and 16O12C17O transitions! that have been excised for visual clarity. Conditions: 2% CO2 seeded in He at 0.8 bar, 20 passes of probe through expansion.