Photo-excitation modelling of the observed (total) column densities as a function of time, as measured in Paper I (see their Table 3), for C ii, Si ii, Fe ii and Fe iii. The open circles are detections, while the open triangles indicate upper or lower limits (3σ). The different colours denote the different ion levels: black for the ground state and red-green-maroon-orange for the first four excited levels, while the Fe ii and Fe iii levels are indicated in blue. The model fit describes the observed column densities very poorly, with a reduced chi-square of .