Internal and external heavy-atom effects on phosphorescence radiative lifetimes calculated using a mean-field spin-orbit Hamiltonian

We investigate the performance of an atomic mean-field approximation to the spin-orbit interaction Hamiltonian in calculations of phosphorescence radi ative Lifetimes. A comparison of the performance of the mean-field approxim ation with the full spin-orbit interaction operator is made for the phospho rescent radiative lifetimes of the B-3(1u) excited state of ethylene pertur bed by an external halogen ion, and for the (3)A(1) and B-3(1) excited stat es in mono- and di-halogen-substituted pyridines. The mean-field approximat ion is shown to give excellent results compared to calculations with the fu ll one- and two-electron spin-orbit integrals. (C) 1999 Elsevier Science B. V. All rights reserved.