Synthesis and characterization of color-stable electroluminescent polymers: Poly(dinaphtho [1,2-a : 1 ',2 '-g]-s-indacene)s

Two new stepladder conjugated polymers, that is, poly(7,7,15,15-tetraoctyldinaphtho[1,2-a:1',2'-g]-s-indacene) (PONSI) and poly(7,7,15,15-tetra(4-octylphenyl)dinaphtho[1,2-a:1',2'-g]-s-indacene) (PANSI) with alkyl and aryl substituents, respectively, have been synthesized and characterized. In comparison with poly(indenofluorene)s, both polymers have extended conjugation at the direction perpendicular to the polymer backbone because of the introduction of naphthalene moieties. The emission color of the polymers in film state is strongly dependent on the substituents. While PONSI emits at a maximum of 463 nm, PANSI with the same backbone but aryl substituents displays dramatically redshifted emission with a maximum at 494 nm.

Thermal Decomposition of 1,2-Dichloroethane in a Single-Pulse Shock Tube

在单脉冲激波管上,研究了1,2-二氯乙烷的热裂解.实验的激波条件为:温度区间1020 K＜T＜1190 K, 压力: P=0.12 MPa,实验时间τ=0.5 ms;实验气体为1,2-二氯乙烷稀释于Ar气中(3.95 mmol/L).以4-甲基-1-环己烯作为对比速率法实验的内标物,用4-甲基-1-环己烯开环反应的速率常数k=1015.3exp(-33400/T) s-1,以及从其产物的浓度推定出实验温度.经激波加热后的实验气体的终产物用气相色谱分析出主要成分为C2H3Cl,指示出主要反应通道为β消去反应.如把所有产物C2H3Cl都归于β消去反应,则可推定出表观之反应速率常数k1a=5.0×1013exp(-30000/T) s-1.对于由C-Cl键断键反应引发的链反应的可能影响做了分析研究.用了一种简便分析可推知在实验的温度范围内的低端(1020 K)链反应的影响可以忽略,而在其高端(1190 K)链反应将给出10%的终产物C2H3Cl的附加浓度,获得真实的β消去反应速率常数则必须把这部分予以扣除.经过这样的校正之后,最后得到CH2ClCH2Clβ消去反应速率常数为k1c=2.3×1013exp(-29200/T) s-1.

Effect of Pb Volatilization on Dielectric Properties of 0.77PbMg1/3(Nb0.9Ta0.1)2/3O3-0.23PbTiO3

Lead magnesium niobate-lead titanate (PMN-PT) is an intriguing candidate for applications in many electronic devices such as multi-layer capacitors, electro-mechanical transducers etc. because of its high dielectric constant, low dielectric loss and high strain near the Curie temperature. As an extension of our previous work on Ta-doped PMNT-PT aimed at optimizing the performance and reducing the cost, this paper focuses on the effect of Pb volatilization on the dielectric properties of 0.77Pb(Mg1/3(Nb0.9Ta0.1)2/3)O3-0.23PbTiO3. The dielectric constant and loss of the samples are measured at different frequencies and different temperatures. The phase purity of this compound is determined by X-ray diffraction pattern. It is found that the volatilization during sintering does influence the phase formation and dielectric properties. The best condition is sintering with 0.5 g extra PbO around a 4 g PMNT-PT sample.

反式和顺式-1，2-二氰-（4-乙基苯）乙烯结构的谱学分析

合成了2种新型的可溶性四氮杂卟啉中间体：反式-1，2二氰-（4-乙基苯）乙烯和顺式-1，2-二氰（4-乙基苯）乙烯。通过UV-Vis，FFIR，GC／MS，^1H NMR等方法对这2种化合物的结构进行了表征，给出了它们完整的结构信息。分析比较了顺、反异构体结构上的差异，分析两者的紫外-可见光谱（UV-Vis）、红外光谱（FTIR）和核磁共振光谱（^1H NMR）谱图的差异及其产生原因。

Infrared (1.2-1.6 mu m) luminescence in Yb, Cr : YAG with 940 nm diode pumping

Infrared (1.2-1.6 mum) luminescence in a yttrium aluminium garnet (YAG) crystal, co-doped with Yb (10 at.%) and Cr (0.05 at.%) ions, was investigated under CW laser diode pumping (lambda = 940 nm). The Cr4+ emission band was observed with its peak at 1.35 mum and measured to be about 6% with respect to Yb3+ IR luminescence (lambda = 1.03 mum). Analysis of the crystal absorption and luminescence spectra allows one to conclude that Yb3+-Cr4+ energy transfer is a mechanism responsible for the B-3(2)(T-3(2))-B-3(1)((3)A(2)) emission of Cr4+ ions. This crystal is promising as an efficient source of the near infrared emission. (C) 2004 Elsevier B.V. All rights reserved.

Infrared (1.2-1.6 mu m) luminescence in Cr4+: Yb3Al5O12 single crystal with 940 nm diode pumping

Infrared (1.2-1.6 mu m) luminescence in a ytterbium aluminium garnet (YbAG) crystal, doped with Cr (0.05 at.%) ions, was investigated under CW laser diode pumping (lambda = 940 nm). The Cr4+ emission band was observed with its peak at 1.34 mu m and measured to be about 1.3 times with respect to Yb3+ IR luminescence (lambda = 1.03 mu m). We demonstrate that for the excitation wavelength of 940 nm Yb3+ ions act as sensitizers of the B-3(2)(T-3(2))-B-3(1)((3)A(2)) emission of Cr4+ ions. This crystal is promising as a high-efficient system for tunable laser (1.2-1.6 mu m) output. (c) 2004 Elsevier B.V. All rights reserved.