Linear relations between vibrational energy levels of CO₂ and fourth order spectroscopic constants

Abstract

We establish the general formula giving the sum of vibrational energy levels belonging to a Fermi polyad, as a function of quantum numbers and spectroscopic constants up to 4th order approximation. This formula makes it possible to write all the linear relations existing between spectroscopic constants (or combinations of spectroscopic constants) and vibrational energy levels.