x-displacement shows a behavior that is qualitatively similar to that of the z-displacement in Fig. . The same holds true for the y-displacement in Fig. , i.e. for the S 0 →S 2 transition. In the case of the S 0 →S 1 shown in Fig. , it turns out that due to the geometry and the spatial form of the involved wave functions (cf. Fig. ), the range of the validity of the dipole approximation sets in only at large distances (see inset of Fig. ).