The carbon dioxide molecule

Abstract

Accurate ground state rotational constants and reliable vibration-rotation interaction constants are available for CO₂ and its isotopomers. Therefore CO₂ has been used as a test case to study the various internuclear distances. We found that the r ₀ distances appear, for a given carbon isotope, as a linear function of the inverse of the reduced mass. The r ₃ distances obtained, even from purely ‘theoretical’ parameters, still show a small isotopic dependence. Finally Watson's method seems to yield, in the present case, r _m distances differing from r _e by only 5 × 10^-5 Å.