Spin–orbit effects in photodissociation of sodium iodide

Abstract

Ab initio configuration interaction calculations of the electronic binding energies, spin–orbit coupling matrix elements and transition dipole moments of NaI are presented. The results are used to construct adiabatic and diabatic representations of the 0+ molecular states relevant to predissociation. The dynamics of photopredissociation is elucidated by multichannel time-dependent wave packet propagation in the diabatic representation. Specific features associated with the spatial and temporal evolution of the wave packet are ascribed to those observed in femtosecond pump–probe experiments. In particular, the rate of decay of the electronically excited NaI* complex is found to be in close agreement with time-resolved experimental studies. Partial photoabsorption cross sections for the production of iodine atoms in the ground (2P3/2) and excited (2P1/2) spin–orbit states are calculated and found to peak at excitation wavelengths of 322 and 263 nm, respectively, in accord with experimental data.