In a recent paper [M. Chrysos, I. A. Verzhbitskiy, F. Rachet, and A. P. Kouzov, J. Chem. Phys. 134, 044318 (2011)], we showed that, in CO₂, the 2_ν3 transition generates a Raman line spectrum that is 98 depolarized, a property in agreement with general symmetry rules. Here, we present an extensive analysis, experimental and theoretical, of the isotropic remnant of this overtone. The isotropic spectrum turned out to be 45 times less intense than its anisotropic counterpart and to have a moment that is 350 times smaller than the moment of the anisotropic spectrum, in excellent agreement with theoretical predictions. Once the measured intensity (along with other data exclusively experimental) was fed back into the formula of the moment, a value for the CO₂ mean-polarizability asymmetric stretch derivative δ²ᾱ/δq₃ ² was returned that matches the best ab initio prediction to better than 4%. Agreement, in order of magnitude, was found between the intensity reported herein and that reported in the sole prior study of this overtone [G. Tejeda, B. Maté, and S. Montero, J. Chem. Phys. 103, 568 (1995)].