The lowest 1(3PJ) and 2(3P2) ion-pair states of ClF: Nonadiabatic effects and emission spectra

Abstract

The structure of the Ω=1,2 states correlating with the F−(1S0)+Cl+(3PJ) ionic products and their emission are studied. Ab initio potential energy curves of ClF published recently and computed electronic dipole moments for parallel transitions between the Ω=1,2 ion pair and valence states, as reported in the present work, are used to calculate vibrational energies and emission spectra in the adiabatic and nonadiabatic approximations. It is shown that spectroscopic and emission properties of the D′2(3P2) state can be quite accurately described in the adiabatic approximation. On the contrary, the G1(3P1) and β1(3P2) states are nonadiabatically mixed due to the strong radial coupling caused by significant variation of the Σ−3 and Π3 Λ–S contributions, similar to that observed for the E0+(3P2) and f0+(3P0) states. Nonadiabatic calculations carried out for the G1(3P1) and β1(3P2) ion-pair states clearly demonstrate the influence of the radial coupling on the emission spectra, although do not reproduce quantitatively the entire range of experimental vibrational energies.