Isotopic composition of CO2?

The wavelength of an absorbed frequency is inversely proportional to the energy of the photon. The m of the carbon atom and the oxygen atoms has a large effect on the energy gap between vibrational states and therefore will impact I would also expect O-17 and O-18 to add an additional absorption band, because, if the two oxygen atoms are not the same isotope, the symmetric C-O stretch will not be perfectly symmetrical because the oxygen atoms have different weights and the center of m of the CO2 molecule will move. This new band would make the isotropically mixed CO2 a much stronger greenhouse gas than normal CO2.