取代基对双酞菁铥LB膜及光谱特性的影响

采用紫外-可见吸收光谱的方法研究了三种稀土夹心双酞菁铥化合物在溶液和LB膜中的聚集性和光谱特性。实验结果表明三种稀土双酞菁化合物在氯仿溶液中形成了H-聚集体,但当浓度比较低时,溶液中表现出单体的吸收。取代基OC₈H₁₇的加入使氯仿溶液中双酞菁铥化合物的聚集性减弱,而且使得吸收峰发生红移,对吸收峰的强度也有较大的影响,造成了Soret吸收带的分裂。另外,取代基OC₈H₁₇对LB膜中双酞菁分子的存在状态有较大的影响,在LB膜中,TmPc₂和TmPcPc*分子以H-聚集体的形式存在,而TmPc*₂分子以T-聚集体的形式存在。形成LB膜后,由于双酞菁分子之间排列紧密,相互作用加强,使得薄膜中分子聚集体的吸收峰相对于溶液中聚集体的吸收峰发生了一定的红移,薄膜中分子排列方向的不同对吸收光谱也有一定的影响。     

一种可溶喹吖啶酮衍生物LB膜的光谱特性

采用表面压-分子面积(π~A)等温曲线、紫外-可见吸收谱和荧光光谱的方法研究了一种喹吖啶酮衍生物材料LB膜的制备及其光谱特性。实验表明,这种喹吖啶酮衍生物能够在水面上形成稳定的单分子膜,它与花生酸(AA)混合后不仅可以形成很好的单分子膜,而且可以较好的转移到固体基片上制备成LB膜多层膜。这种喹吖啶酮衍生物LB膜的紫外-可见吸收谱的吸收峰位较稀溶液发生了红移,这是由极性溶剂分子与其相互作用的结果。其溶液有很强的荧光效应,但LB膜没有荧光现象,原因是在LB膜中QAC16的浓度过高发生“自我猝息”而失光。它在溶液和LB膜中都是以单体的形式存在。     

螺芴氧杂蒽LB膜的制备及光谱特性研究

为了研究聚芴材料DSFX-SFX分子在气液两相表面的行为,分子处于溶液、LB膜及粉末状态的光学特性,以及分子有序排列对其发光特性的影响,制备了聚芴材料DSFX-SFX的X型LB膜,研究了π-A等温曲线,测量了其紫外-可见吸收谱和稳态荧光光谱。结果表明,分子以face-on形式平躺在亚相表面,单分子面积为4.78 nm2。在氯仿溶液中吸收峰位在354 nm,归属于分子中三聚氧杂蒽部分与芴环间π-π*电子跃迁;荧光发射峰位在396,419,445 nm(肩峰),归属于发色团三聚氧杂蒽,是芴环与氧杂蒽环之间的电荷转移。在LB膜中,吸收谱和荧光光谱与其溶液光谱相比,整体红移6 nm。结果表明:在LB膜中,两个分子形成激基缔合物,与单分子状态相比,激基缔合物的HOMO升高而LUMO降低。与粉末状态相比,该材料在LB膜中有很强的荧光发射,表明该材料形成有序排列超薄膜有利于荧光发射。     

一种液晶化合物LB膜中的分子取向及膜结构

"利用LB技术制备出MPUOPM的Langmuir和LB膜．随着表面压力的升高,在?-A曲线上的可观察到一个明显的折点．通过与分子刚性基团的理论截面积相比较,发现该折点反映的是单层膜向多层膜的转变．紫外可见、偏振红外等光谱被用来研究膜的结构,发现烷基链与基片法线夹角为48o,C＝N基团互相平行,与基片法线呈51o夹角排列．"     

LB膜的制膜条件优化及其对光学性能的影响

通过紫外-可见吸收光谱、二次谐波振荡和稳态荧光的测量,研究了半花菁(DAEP)Langmuir-Blodgett(LB)膜在不同制膜条件(压膜速度、半花菁和花生酸混合、亚相中加入碘离子)下,LB膜样品中半花菁分子的聚集体性质的改变和对非线性光学性能的影响.实验发现,纯半花菁LB膜中分子形成H-聚集体,从而导致吸收峰、荧光峰的蓝移和分子二阶非线性极化率β的减少.分子聚集程度的减少和分子二阶非线性系数β的增加可以通过增大压膜速度、半花菁和花生酸混合、亚相中加入碘离子等方法实现.     

紫外光照射对LB膜光学性质的影响

通过紫外-可见吸收光谱、时间分辨荧光和旋转样品二次谐波方法研究了半花菁和花生酸交替LB多层膜在偏振紫外光照射下的光诱导各向异性. 实验发现, 在ns紫外偏振光照射下, LB多层膜中分子发色团长轴向照射光偏振方向重新取向, 并使H聚集体程度增强.     

两种烷基取代喹吖啶酮衍生物LB膜的荧光特性

制备了两种烷基取代喹吖啶酮衍生物C6DHQA和C16DMQA的X型Langmuir-Blodgett(LB)膜,采用紫外-可见吸收、稳态荧光和时间分辨荧光的方法研究其溶液及LB的光学特性。研究结果表明,C16DMQA比C6DHQA的吸收谱整体红移,说明烷基链加长减小了分子的能级间隔;两者LB膜的吸收谱较溶液整体红移,说明在LB膜中形成了"J-聚集体"。两种材料的溶液及LB膜都有较强的荧光发射,溶液的荧光谱与吸收谱有很好的镜像对称关系,形成LB膜后,镜像对称关系被打破,两者第三个荧光峰相对强度差别很大。C6DHQA溶液中的荧光寿命为21ns左右,C16DMQA溶液中的荧光寿命为22ns左右,形成LB膜后,荧光寿命明显较少,两者第三个荧光峰对应的荧光寿命差别较大。其原因应归于C16DMQA分子在基板上的排列更密,分子间的相互作用力强,从而对能级结构的影响更大。     

有机分子多层LB膜中聚集体理论和实验研究H

文中采用经典偶极相互作用模型讨论了多层Z型LB膜中分子聚集体的类型 ,给出了分子偶极相互作用能的表达式;并对理论结果与紫外可见吸收光谱的实验值进行了比较,理论结果和实验值符合较好.     

4-硝基-4′-氨基偶氮苯的光学性质研究

采用紫外可见吸收和二次谐波产生技术研究了“推-拉”型偶氮苯分子Langmuir-Blodgett(LB)膜的光谱和二阶非线性光学特性.4-硝基-4′-氨基偶氮苯(NAA)分子能制成很好的LB多层膜,在稀溶液中以单体的反式异构体形式存在,在膜中主要以J-聚集体的形式存在,LB膜的紫外可见吸收谱的吸收峰较之溶液的发生了52 nm的红移.NAALB膜的二阶非线性极化率χ(2)为19.59×10－8 esu,一阶超极化率β值较大,约为1.974×10－29 esu.其光学二阶非线性起源于电偶极子机制.     

紫外-可见吸收光谱法研究细胞色素C活性中心铁离子与微量元素的相互作用

应用紫外－可见吸收光谱法研究细胞细色素C（Fecty-C)活性中心铁离子在pH7．1的磷酸缓冲液中与4种微量元素M（Ⅱ）的直接相互作用。结果表明,细胞色素C（Fecyt-C)活性中心Fe(Ⅱ）离子可被微量元素M（Ⅱ）部分取代,形成部分的细胞色素C衍生物（Mcyt-C),溶液的吸收光谱的Soret带最大吸收峰发生蓝移,且α带与β带最大吸收峰相对峰强减弱。     

半花菁LB膜的时间分辨荧光研究

利用紫外－可见吸收,稳态和时间分辨荧光等方法研究了半花菁与花生酸交替Ｙ型ＬＢ膜中分子聚集体的性质;吸收光谱和稳态荧光光谱峰位的蓝移说明ＬＢ膜中Ｈ聚集体的存在。从荧光衰工线得到了聚集体的组份含量、大小和寿命。     

Formation of nanoscale aggregates of a coumarin derivative in Langmuir–Blodgett film

In the present communication, we report the formation of organized nanoscale aggregates of a coumarin derivative 7 Hydroxy-N-Octadecyl Coumarin-3-Carboxamide (7HNO3C) at the air–water interface and in Langmuir–Blodgett (LB) films in the presence and absence of stearic acid (SA). A pressure-area isotherm reveals that the 7HNO3C form stable monolayer at the air–water interface. However, the stability can be improved by mixing it with a fatty acid stearic acid (SA). The miscibility study shows that the nature of interaction is strongly dependent on the mixing ratio and surface pressure. At a mole fraction of 0.4 of 7HNO3C in SA, the attractive and repulsive interaction between these two molecules balance each other forming a stable film with nanoscale aggregates. UV-Vis absorption spectroscopic studies reveal the nature of the aggregates in LB films. Scanning electron microscopy gives compelling visual evidence of formation of nanoscale aggregates in the mixed LB films.     

Absorption Spectral Study of Mixed Chiral Amino Acid Porphyrin Langmuir-Blodgett Films

Absorption spectra were performed on Langmuir-Blodgett films of a new chiral amino acid porphyrin (Py) and its mixture with stearic acid (SA). Vertical uniformity of the LB films has been demonstrated by the linear relationship between the absorbance and the layer number of films. J-Aggregates were present when the film was transferred at various surface pressures and at different molar ratios of Py and SA. However, no aggregation was present for the molecules in the adjacent monolayers. the observed optical absorption spectra of mixed films were markedly dependent on the combination of Py. When the molar ratio of Py was increased from 0.05 to 0.75, the absorption peaks of Soret and Q bands bathochromically shifted ca. 5.5 and 2.2 nm. When the deposited pressure was increased from 5 to 35 mN/m, the absorption peaks of Soret and Q bands bathochromically shifted ca. 3.7, 3.2 nm and 3.5, 2.2 nm for pure Py and 1:3 Py-SA mixed LB films, respectively. on a hydrophobic substrate, the LB films showed a red shift of ca. 4.5 nm for Soret band compared with that on the hydrophilic substrate owing to their different environments.     

温度对半花菁LB多层膜的光致荧光特性的影响

利用稳态荧光谱和时间分辨荧光技术研究了温度对半花菁Langmuir-Blodgett(LB)多层膜光致荧光特性的影响.半花菁分子在半花菁/花生酸、半花菁/花生酸镉交替及纯半花菁Z-型LB多层膜中均形成了H-聚集体,加热能使聚集体部分离解.由于Z-型膜中没有花生酸或花生酸镉的屏蔽,分子间具有较强的偶极相互作用,加热使聚集体的离解的程度较小.镉离子的加入对半花菁LB多层膜的稳态荧光谱也有一定的影响.     

Photophysical characterizations of 2-(4-biphenylyl)-5 phenyl-1,3,4-oxadiazole in restricted geometry

Langmuir and Langmuir-Blodgett (LB) films of non-amphiphilic 2-(4-Biphenylyl)-5-phenyl-1,3,4-oxadiazole (abbreviated as PBD) mixed with stearic acid (SA) as well as with the inert polymer matrix poly(methyl methacrylate) (PMMA) have been studied. Surface pressure versus area per molecule (π-A) isotherm studies suggest that PBD molecules very likely stand vertically on the air-water interface and this arrangement allows the PBD molecules to form stacks and remain sandwiched between SA/PMMA molecules. At lower surface pressure, phase separation between PBD and matrix molecules occurs due to repulsive interaction. However, at higher surface pressure, PBD molecules form aggregates. The UV-vis absorption and steady-state fluorescence spectroscopic studies of the mixed LB films of PBD reveal the nature of the aggregates. H-type aggregate predominates in the mixed LB films, whereas I-type aggregate predominates in the PBD-PMMA spin-coated films. The degree of deformation produced in the electronic levels are largely affected by the film thickness and the surface pressure of lifting.     

Role of various LB parameters on the optical characteristics of mixed Langmuir-Blodgett films

This communication reports the spectroscopic characterizations of mixed Langmuir-Blodgett (LB) films of non-amphiphilic N,N-bis (2,5-di-tert-butylphenyl)- 3,4,9-perylenedicarboximide (DBPI) molecules, mixed with polymethyl methacrylate (PMMA) and stearic acid (SA). J- aggregates of DBPI molecules in the mixed LB films have been confirmed by UV-Vis absorption spectroscopic study. Formation of organized structure of molecular stacking in the mixed LB films gives rise to the strong excimeric emission, which is manifested by a broad structureless band in the longer wavelength region of the fluorescence spectra and is confirmed by excitation spectroscopic study. A weak hump at around 576 nm due to monomeric emission is observed in the fluorescence spectra of 0.1 M of DBPI-PMMA mixed LB films of lower number of layers. The intensity of the 0-0 band at 530 nm in the fluorescence spectra is observed to be a function of the molefraction, number of layers, surface pressure of lifting and the matrix materials.