摘要
Sum-frequency generation (SFG) vibrational spectroscopy was used to probe ultraviolet (UV) photo-induced bond breaking and anisotropy on PMDA-ODA surfaces that allow god liquid crystal (LC) homogeneous alignment. Bond breaking of the polyimide (PI) backbones taking place in the part of the phenylene rings and imide core was observed. By analyzing the experimental results from a rubbed surface before and after the photo-induced bond breaking, it was possible to deduce information about the surface orientations of the PI backbones and the photo-dissociation rates for UV irradiation polarized parallel and perpendicular to the PI backbones.