Figure 1. The (v1, 2v2) infrared band of CO2. (a) Ob- served spectrum (I = 56 m, ρ = 0.92 amagat, T = 1920K). (b) Profile with the (v1, 2v2) band of C16O18O removed. (c) Calculated pressure-induced profile for free-free collisions. (d) (= (b) - (c)) Spectrum ascribed to the (CO2)2 dimer. (e) The v1d band with assignments of the maxima.