On the vibration-rotational matrix elements for diatomic molecules

Abstract

Theoretical expressions for the vibro-rotational matrix elements of powers of the reduced displacement from equilibrium, corresponding to the infrared and Raman transitions vJ→ v′J′ with v′⩽ v+4, are obtained in terms of quartic polynomials in m (or J), including contributions from theDunham potential-energy coefficients a 1, a 2, a 3. It is shown that it is preferable to consider the coefficients of the vibration-rotation interaction function [F v′ v(m)] 1 2 rather than the Herman-Wallis factors. Two formalisms derived from power series expansion of the vibration-rotational internuclear potential function have been applied to the infrared transitions v→ v′ (with v = 0, 10, 20) of the ground electronic state of CO.