Configuration interaction calculations on the X 1 Sigma + ground state and low-lying A 1 Pi and 1 Delta excited states of the PN molecule. II. Potential energy curves of the A 1 Pi and 1 Delta excited states of PN and spectroscopic properties

Abstract

For pt.I see ibid., vol.25, no.21, p.4433-46 (1992). CI calculations have been performed on the A 1 Pi and 1 Delta states of PN in the vicinity of their respective equilibrium geometries, yielding spectroscopic constants in good agreement with the available experimental data. The 1 Delta state, which is unknown experimentally, is predicted to lie less than 500 cm-1 above the 1 Pi state and 40345 cm-1 above the 1 Sigma + ground state. Theoretical vibrational bands for the A 1 Pi to X 1 Sigma + transition were computed, along with the corresponding Franck-Condon factors. The calculated vibrational transitions agree quite well with the observed values while the Franck-Condon factors compare favourably with those calculated semiempirically from observed vibrational transition probabilities. Spontaneous radiative and non-radiative lifetimes derived according to two decay mechanisms-a cascade (A 1 Pi state being 'isolated') mechanism and an electric dipolar transition mechanism-show that the latter mode of decay is several orders of magnitude larger. The single experimentally known lifetime value, i.e. for nu '=0, issued from this decay mode agrees reasonably well with the calculated value.