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inter_dudu木虫 (著名写手)
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【求助】求助紫外光谱
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小弟光谱分析没学好。。文献看不懂。。 向各位大哥大姐求教这图啥意思。。The absorption spectra of 1, CR1, [Eu(tta)3], and acidified N-(Rhodamine-6G)lactamethylenediamine are shown in Figure 2. Free CR1 displays an intensive absorption band in the visible region centered at 415 nm that arises from the coumarin chromophore (Supporting Information Figure S5.1) and a weak band at about 302 nm, which is attributed to absorption of the ring-closed tautomeric form of the Rhodamine 6G moiety (Supporting Information Figure S5.2). The UV/Vis absorption spectrum of 1 displays three main absorption bands centered at 345, 415, and 525 nm. By comparison of the absorption spectra of [Eu(tta)3], CR1, and 1, the first two were mainly assigned to the characteristic absorption maxima of the Eu-TTA moiety and the coumarin chromophore, respectively. The last band, which is absent in CR1, should be assigned to the absorption of the ring-opened tautomer of the Rhodamine 6G chromophore,[14] that is, the carbonyl group of the Rhodamine 6G moiety is coordinated to the Eu center and the attached spiro ring has opened to make green emission of 1 possible. Thus, 1 exhibits characteristic blue emission of the coumarin fluorophore centered at 460 nm, green Rhodamine emission centered at 550 nm, and typical red emission of the EuIII ion with dominant peak at 612 nm when its solution in acetonitrile (50 mm) is excited at 415, 525, and 360 nm, respectively (Figure 3). The quantum yields of the blue, green, and red emissions are about 0.056, 0.085 and 0.005, respectively.[15] While a few organic dyes have been reported that exhibit tunable emissive properties,[8a] the generation of pure blue, green, and red emissions in a single-component dye by simply changing the excitation wavelengths is extremely appealing and significant. Such color-tunable materials may be promising candidates for emitting “pure” white light by controllably tailoring blue, green, and red primary colors that fully span the entire visible spectrum. |
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Charles911
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2楼2009-08-25 17:05:48
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4楼2009-08-25 17:55:32
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5楼2009-08-25 21:08:49
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inter_dudu(金币+15,VIP+0): 8-26 13:43
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图2为这四种物质的吸收光谱，从图中可看出，CR1在415nm可见区内有较大吸收，在302nm处有弱吸收，其中415nm处的峰是由香豆素（coumarin chromophore）内电子跃迁产生，（由图 S5.1可知），302nm处的峰则来自闭环的若丹明异构体（the ring-closed tautomeric form of the Rhodamine6G moiety ）产生，（由图S5.2可知） 1在345nm，415nm和525nm处均有吸收峰，比较[Eu(tta)3], CR1, 和1三种物质的吸收峰，[Eu(tta)3]和CR1分别在345nm，415nm有吸收。在525nm处CR1没有吸收峰，这是由于若丹明生色团开环造成的，也就是说，若丹明6G基团的羰基与Eu中心结合，形成螺环使1有可能发射绿光。（注：525nm处为绿光）因此，由1可看出发出蓝光的香豆素荧光中心位置在460nm，绿色若丹明发射中心在550 nm，而EuIII离子典型的红色发射主峰在612nm。而它溶解在乙腈中（50mm）则分别发出415，525和360nm的光（见图3），蓝色、绿色和红色的量子产率分别为0.056，0.085和0.005，有报导说个别有机染料具有可调发射特性，在单一组分染料中通过改变激发波长得到纯蓝色，绿色和红色光及具有吸引力和重要性，这种颜色可调材料可能成为发射白光的候选物质，因为能完全跨越整个可见光谱的蓝色，绿色和红色三种主要颜色能够形成白光。 |
6楼2009-08-26 12:17:51
