Vibration-rotational matrix elements for infrared transitions of diatomic molecules

Abstract

Theoretical expressions for the vibro-rotational matrix elements corresponding to i.r. transitions vJ→ v′ J′ with v ⩽ v ′ ⩽ v + 6 are obtained in terms of quadratic polynomials in m, including contributions from the Dunham potential energy parameters a 1 to a 5 and from dipole-moment expansion coefficients M 0 to M 7. The formalism has been applied to vibrational transitions in the ground electronic state of CO and HCl. The Herman-Wallis coefficients have been derived for the bands 0-0 to 0-4 of CO and 0-0 to 0-6 of HCl and are compared with experimental data.