Wigner Time Delay in the Photodetachment of Li^- in the Threshold Region

We have performed R-matrix calculations for Li^- photodetachment to determine the Wigner time delays associated with leaving the Li atom in the ground and the first few excited states. Our computed dipole matrix elements are first validated through cross section comparisons with experimental data and previous theoretical results.  Dramatic variations in the time delay are observed near excitation thresholds, with increasing complexity occurring as the energy increases.