有機非線性光學材料DAST在膠體中長晶的研究

Studies into the Growth of DAST Crystals in Gels

李建德(Jian-De Lee)

指導教授 ： 余琬琴

國立臺北科技大學/工程學院/有機高分子研究所/碩士(2007年)

摘要

有機非線性光學晶體材料-DAST(4-dimethylamino-N-methyl-4- stilbazolium tosylate) 因擁有相當大的非線性光學係數，光電係數與低介電常數等特性，所以是目前最被看好的新材料之一，在光通訊、光學計算與資訊儲存方面有很高的應用價值，然而從溶液中生長DAST單晶的傳統方式，不容易得到大面積高品質的DAST單晶，這將會限制其應用潛力，因此亟待開發更有效率的DAST單晶製備方法。
針對DAST單晶製備不易的問題，本論文開發一種在膠體中生長DAST晶體的新穎方法。與溶液長晶法比較，在膠體中的物質輸送僅靠擴散，這使得晶體的生長較為穩定，應有助於提升晶體品質，事實上在膠體中長晶的方法已被廣泛地應用在蛋白質晶體，也常應用在一些不容易製備的晶體材料。本研究使用雙擴散法，我們將膠體置於U型管的底部，然後在膠體兩側分別加入合成DAST的兩個反應物：4-methyl-N-methyl pyridinium tosylate與4-N,N-dimethylamino- benzaldehyde 的溶液，反應物從U型管兩端擴散至膠體中反應形成DAST晶體。我們將探討反應物濃度與比例，以及催化劑濃度對晶體分佈與品質的影響，並使用電子顯微鏡、X-ray繞射儀及光譜儀等儀器對晶體的各項性質進行量測。

關鍵字

非線性光學 ； 膠體生長 ； 溶解度 ； X-ray繞射 ； 型態

並列摘要

DAST(4-N,N-dimethylamino-4’-N’-methylstilbazolium tosylate), one of the most promising organic nonlinear optical materials, is well known for its large nonlinear optical susceptibility and high electro-optical coefficient. DAST bulk crystals are usually grown from saturated methanol solutions by slow cooling. However, the growth of high quality DAST crystals form solutions remains difficult. Here we present a novel double diffusion method for growing DAST crystals in gels. In this method, the middle section of a U tube was filled with a gel matrix. The two reactants, 4-methyl-N-methyl pyridinium tosylate and 4-N,N-dimethylamino-benzaldehyde, were individually dissolved in an organic solvent and layered onto the gel, one in the left arm and the other in the right arm of the U tube. These two reactants were allowed to diffuse into the gel matrix, where they reacted to form DAST. When conditions were favorable, nucleation occurred and crystals formed in the gel matrix. The X-ray powder diffraction study confirmed the structure of the resulting DAST crystals. Results showed that crystal size, number and morphology all varied with positions in the U tubes. We also investigated the effects of reactant concentrations and ratio, as well as the concentration of catalyst, on crystal distribution, morphology and quality. Optical and scanning electron microscopy was used to examine the surfaces of the grown crystals. The transmittances of the grown crystals were also determined.

並列關鍵字

Nonlinear optical ； gel growth ； solubility ； X-ray diffraction ； morphology

參考文獻

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