Potential energy curves and spectral properties for electronic states of F 2 and F +2

Abstract

Potential energy (PE) curves for the Rydberg states of F 2, and for the ground and lowest two electronic states each of symmetry 2Π g,u, 2Δ g,u and 2Σ ± g,u of F + 2, have been obtained using modest-sized configuration-interaction calculations. These PE curves have been used to calculate spectroscopic constants for the electronic states and the results agree reasonably well with the limited experimental and theoretical results previously reported. The theoretical PE curves for the Rydberg states of F 2 are found to be strongly perturbed by valence-Rydberg-ionic interactions and these perturbations appear to be responsible for certain features in recently reported electron energy-loss spectra in F 2. The corresponding electronic wavefunctions have been used to calculate the electronic transition moment, as a function of the internuclear distance, for dipole-allowed transitions between the lowest excited electron state of each symmetry and the appropriate ground electronic state. The radiative emission probabilities, natural lifetimes, and absorption oscillator strengths, for each band system, are also reported here. The predicted lifetimes for vibrational levels of the A 2Π u of electronic state in F + 2 vary from 1.3–1.5 μs and agree reasonably well with the single available set of measurements. The predicted radiative lifetimes for the higher electronic states of F + 2 are substantially longer and fall into the range 5–100 ms.