Fig. 6

AFM and FFT images of sample 1 with d=101 nm (a-d) and d=493 nm (e-h). The samples a), c), e), and g) have been irradiated for 30 min and b), d), f), and h) for 60 min with linear polarization (a, b, e, f) and circular polarization (c, d, g, h). The bump structures are very well pronounced and confirmed by their FFT images (a-d). In case of irradiation with CPL the bump structures are not hexagonal ordered as in a) and b), but randomly distributed with an average distance Λ between the bumps (see Table 2). In e) and f), the bump structures seem like fused to parallel rib structures and have similar distances