A recently developed time dependent model for the excitation of a nucleon from a bound state to a continuum resonant state in the system n+core is applied to the study of the population of the low energy continuum of the unbound $^{10}$Li system obtained from $^{11}$Li fragmentation. Comparison of the model results to new data from the GSI laboratory suggests that the reaction mechanism is dominated by final state effects rather than by the sudden process, but for the population of the l=0 virtual state, in which case the two mechanisms give almost identical results. There is also, for the first time, a clear evidence for the population of a d$_{5/2}$ resonance in $^{10}$Li.

15 pages, 4 figures, 3 tables. Accepted for publication in Nucl.Phys.A