Figure 2. Crystal orientation and deformation.

(a–f) Motion of the crystals when the longer diagonal axis of the crystal is (a–c) parallel and (d–f) perpendicular to the direction of irradiation. Laser microscope images of DMAB crystals before (a,d) and after (b,e) irradiation for 2 min. Slight deformations of the crystals are observed during the motion. Note that the crystals moved ca. 3 μm. Irradiation conditions: θ_UV=θ_VIS=30°, ϕ=180°, intensities of UV and visible light are 200 and 100 mW cm⁻², respectively. (c,f) Schematic diagrams of the motion and the direction of light. (g) Optical photomicrograph of the crystal showing the crystal faces. (h) Schematic representation showing the molecular packing and crystal faces based on X-ray diffraction experiments.