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Metal-phthalocyanines are known to be a functional organic material. We reported some remarkable nonlinear optical properties of tin-phthalocyanine whose center atom is tin. Tin-phthalocyanine thin films were fabricated by a vacuum evaporation method and its third-order nonlinear susceptibility was estimated. The substrate was a glass plate with coated rubbing treated polyimide thin films (called the rubbing plate) to orientate microcrystalline axis. The values of the third-order susceptibility were the order of lo-'' esu by using a THG Maker-Fringe method and these were several times as large as those evaporated on substrate which was not rubbed.In order to control microcrystalline orientation without the rubbing plate, the glass plate with only IT0 coated was used and an electric field, which was normal to the substrate surface, was applied during evaporation. We observed surface structure of these films using AFM, and measured optical absorption spectra. As a result, no remarkable anisotropy was found, but it was confirmed that absorption peak of Q-band was blue-shifted and its relative intensity was changed. Moreover, the values of third-order susceptibility were measured by using a z-scan technique and these were almost the same as those of the films fabricated on the rubbing plate. Reference system ersonal Computer w Sample SHGl165"m) P40 Fig. 1. Block diagram of the experimental setup.energy of the excitation light was 2.33 eV. All experiments were performed in air at room temperature. The sample was a rutile Ti0,(110) single crystal whose surfaces were mechanically polished and chemically etched.In Fig. 2 we show the azimuthal angle dependence of the SH intensity from the single crystal TiO,(llO) obtained in our experiment. The azimuthal angle is the angle between the incident plane and the [IT01 direction. The SH intensity is plotted along the radial direction.We discuss briefly whether the observed SHG is radiated by the bulk electric dipole, surface electric dipole, or bulk electric quadrupole. Since the crystalline structure of rutile TiO, has an inversion symmetry, the observed SHG is not from the bulk electric dipole from symmetry considerations. Also, comparing the observed radiation patterns with the theoretical calculation, we found that the observed SH light is not radiated by the bulk electric quadrupole. Thus, we consider below the SH intensity patterns from the surface electric dipole polarization.The surface nonlinear polarization can be written:, Azimuthal angle dependence of the optical second harmonic intensity from the rutile TiO,(l 10) single crystal Eiichi Kobayashi, Goro Mizutani," Sukekatsu Ushioda, School of Materials Science, Japan Advanced Institute of Science and Technology, Tatsunokuchi-machi, Nomigun, Ishikawa-ken 923-12, JAPAN TiO, is a well-known photocatalyst for water decomposition. The understanding of its surface is very important, because the photocatalyzed reaction occurs on the surface. As one of the surface probes for such an investigation, optical second harmonic gen...