Photoinduced intramolecular charge transfer and S2 fluorescence in thiophene-pi-conjugated donor-acceptor systems: experimental and TDDFT studies

Experimental and theoretical methods were used to study newly synthesized thiophene-pi-conjugated donor-acceptor compounds, which were found to exhibit efficient intramolecular charge-transfer emission in polar solvents with relatively large Stokes shifts and strong solvatochromism. To gain insight into the solvatochromic behavior of these compounds, the dependence of the spectra on solvent polarity was studied on the basis of Lippert-Mataga models. We found that intramolecular charge transfer in these donor-acceptor systems is significantly dependent on the electron-withdrawing substituents at the thienyl 2-position. The dependence of the absorption and emission spectra of these compounds in methanol on the concentration of trifluoroacetic acid was used to confirm intramolecular charge-transfer emission. Moreover, the calculated absorption and emission energies, which are in accordance with the experimental values, suggested that fluorescence can be emitted from different geometric conformations. In addition, a novel S(2) fluorescence phenomenon for some of these compounds was also be observed. The fluorescence excitation spectra were used to confirm the S(2) fluorescence. We demonstrate that S(2) fluorescence can be explained by the calculated energy gap between the S(2) and S(1) states of these molecules. Furthermore, nonlinear optical behavior of the thiophene-pi-conjugated compound with diethylcyanomethylphosphonate substituents was predicted in theory.     

Squeezing of Phonons in Photon-Phonon Interaction via Anti-Stokes Light

A model of the photon-phonon interaction via anti-Stokes light has been proposed to investigate the squeezing properties of phonon mode. The behavior of initial anti-Stokes light with complex statistics has been studied. It is shown that the squeezing of phonon mode can appear under certain conditions.     

Electrochemical and Spectral Studies on Ferrocene Derivatives with Electron Pushing and Drawing Substituents

Three ferrocene derivatives, P Ⅰ: R-Fc-A, P Ⅱ:D-Fc-R and P Ⅲ: D-Fc-A(R:CH₂OH, A: CH＝C(CN)CONH₂, D:(C₁₈H₃₇)₂-C₆H₄-CH=CH), were studied by means of cyclic voltammetry and absorption spectroscopy. Compound P Ⅰ shows MLCT transition,P Ⅱ D shows strong LMCT and P Ⅲ shows both strong LMCT and π→π^* CT transitions. Based on these data, frontier orbital interactions of electron pushing and drawing substituents with ferrocene group were analyzed. It was found that a drawing substituent would lower the π^* orbital energy level and a pushing, substituent would raise the π orbital level.     

A Novel Amphiphilic Push-pull Ferrocene Derivative: Langmuir-Blodgett Films and Second-order Optical Nonlinearity

We investigated Langmuir-Blodgett(LB) films built from the mixture of an amphiphilic push-pull ferrocene derivative(P) and behenic acid. Langmuir films of P diluted by behenic acid exhibit a very good cohesion, and the mixed films can easily be transferred onto solid substrates. Linear dichroism UV-visible and IR spectroscopy measurements of the mixed LB multilayers confirm that the molecules(P) are oriented to the substrate. The nonlinear optical experiments on the mixed monolayer deposited on the CaF₂ slide showed that P displays efficient optical second harmonic generation(SHG) with a molecular hyperpolarizability (β)h, high as 6.0×10^-29e. s. u..     

N-二异丙基磷酰基氨基酸的电子电离和快原子轰击质谱的比较

N-二异丙基磷酰基(DIPP)氨基酸的快原子轰击(FAB)和电子电离(EI)质谱都有相似的丢失两分子丙烯和一分子甲酸的碎裂过程.在FAB中,连续失掉两个丙烯,然后脱去甲酸的过程较为有利;在EI中则主要为先脱去甲酸,随后失去丙烯,本文对DIPP-氨基酸的FAB和EI质谱碎裂历程进行了比较,对分子离子峰的形式与碎裂方式的关系进行了讨论.     

β-SiC薄膜在SF6和SF6+O2中的等离子体刻蚀研究

以SF₆和SF₆+O₂为刻蚀气体,采用等离子体刻蚀工艺成功地对化学气相淀积工艺制备的β-SiC单晶薄膜进行了有效的刻蚀去除.实验指出当气体混合比约为40%时,刻蚀速率达到最大值.俄歇能谱分析表明,在SF₆和SF₆+O₂气体中被刻蚀后的样品没有形成富C表面的SiC层.研究结果为各种SiC器件的研制奠定了必要的实验基础. 关键词：     

捷联惯导系统静基座解析粗对准的误差研究

本文讨论了两种陆用捷联惯导系统（ＳＤＩＮＳ） 在静基座情况下解析粗对准的计算方法,求解载体到导航坐标系的变换矩阵时,选择不同的参考矢量将导致失准角不同。计算和仿真结果对比给出了形象的说明。     

氢化物发生-原子荧光光度法直接测定环境土壤中的痕量锗

试样采用硝酸+氢氟酸+高氯酸+磷酸分解至冒尽白烟,在磷酸介质中,不经分离富集,直接在原子荧光光度计上进行测定.方法简捷快速,成本低,结果经国家一级标准物质验证准确、可靠,适合于批量样品的分析测定.本法检出限为0.072 g/g,方法精密度(RSD%,n=8)为4.5%。     

混合碳链烷基聚葡糖苷中相微乳液的研究

用Winsor型相图、δ—γ“鱼状”相图和改进的ε—β“鱼状”相图研究了混合碳链烷基聚葡糖苷(APG：C8／10G1.31和C12／14G1．43)中相微乳液的相行为,结果表明,随醇浓度的增加,微乳液类型发生Winsor Ⅰ→Ⅲ→Ⅱ的转变,从Winsor型相图直接观察到醇浓度增加时,微乳液三种类型的变化、各相体积以及中相微乳液形成和消失时醇的浓度,从“鱼状”相图除得到中相微乳液形成和消失时的组成,以及单相微乳液形成时的组成外,还可得到平衡界面膜的组成、表面活性剂单体分子和醇在油相中的溶解度及表面活性剂形成单相微乳液的效能等,在比较上述两种相图优缺点的基础上,我们首次提出了改进的“鱼状”相图,把两者的优点集中于该图中,既能直观地观察出体系相态的变化,又能得到平衡界面膜的组成等其它性质,为理论和实际应用提供更多信息和方便。     

纳米金修饰玻碳电极固载抗体电位型白喉类毒素免疫传感器的研究

将巯基乙胺 (AET)固载到玻碳电极 (GCE)表面 ,进而化学吸附纳米金 (NG) ,并通过半胱氨酸 (Cys)用戊二醛 (GA)作交联剂将白喉抗体 (anti Diph)固定在玻碳电极上 ,从而制得高灵敏电位型白喉类毒素 (Diph)免疫传感器 .通过循环伏安法考察了电极表面的电化学特性 ,并对该免疫传感器的性能进行了详细的研究 .该传感器对白喉类毒素检测的线性范围是 2 4～ 60 0ng·mL-1,斜率为 3 8.9mV/decade ,线性相关系数为 0 .9979,检出限为 5 .2ng·mL-1,并将其用于生物制品中白喉类毒素的检测 ,其结果令人满意