Structures and nonlinear optical properties of 4-(N,N-dimethylamino)-3-acetamidonitrobenzene films prepared by vapor deposition

4-(N,N-dimethylamino)-3-acetamidonitrobenzene (DAN) was evaporated onto a glass plate and a cleavage surface of KCl in vacuo. DAN films deposited on the glass plate were composed of randomly oriented laminate crystallites. The DAN film deposited on KCl substrate, on the other hand, was composed of tabular crystallites crossing orthogonally. The (001) plane of the DAN crystal lay parallel to the substrate surface, and its a axis oriented parallel to the [110] directions of the KCl substrate. The second harmonic (SH) intensities of DAN films were measured. When the film deposited on KCl substrate was rotated around an axis coinciding with the laser beam propagation direction, the SH intensities of the film changed periodically corresponding to the molecular configuration in the film. The biorientational order of DAN crystal observed by electron microscopy on KCl substrate was confirmed on a macroscopic scale by second harmonic generation.