| Summary: | 碩士 === 國立臺北科技大學 === 有機高分子研究所 === 96 === There has been considerable research interest in organic nonlinear optical（NLO） materials mainly because of their potential for various applications in optoelectronic and photonic devices. Compared to their inorganic counterparts, well-designed organic NLO materials can have much larger optical nonlinearities. A notable example is DAST（4-dimethylamino-N-methyl-4-stilbazolium tosylate）, which has been shown to exhibit a very large second-order nonlinear optical coefficient of about 10 times that of the inorganic standard LiNbO3. However, the reproducible growth of high quality, large DAST crystals remains a challenging task. Through molecular engineering, it is possible to get new materials that possess better optical properties and growth characteristics.
Recently Coe et al. reported a new stilbazolium salt DAPSH （trans-4’- dimethylamino-N-phenyl-4-stilbazolium hexafluorophosphate）, which was shown to possess a very high SHG activity. The Kurtz powder test studies indicated that the new salt has a pronounced SHG coefficient of 470 times that of urea, similar to that of DAST. Because the effective utilization of any NLO crystals for any conceivable application demands high quality crystals, it is required to develop crystal growth process for DAPSH.
In this study, DAPSH crystals were grown from acetonitrile solutions by the temperature lowering technique. The solubility of DAPSH in acetonitrile was determined. The as-grown crystals were subjected to both structural and optical property studies, including x-ray diffraction, UV-visible spectroscopy, and electron microscopy analyses.
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