光电子材料光学参数的无损检测

利用消光式椭圆偏振光谱法 ,在室温下可见光区对光电子材料镓铟磷的光学参数进行了测量 ,得到该材料的折射率和吸收系数随光子能量的变化关系曲线 ,并对结果进行了分析和讨论 ,给出了镓铟磷带隙的位置     

氮的三原子化合物的从头算及密度泛函研究

在6－311＋G＊基组水平上,对氮的三原子化合物N3^-、N3、N3^+,用MP2及六种密度泛涵方法进行了研究。结果表明,对于已知结构的化合物和计算结果与实验测定值非常吻合,对实验上未知的化合物分子的稳定几何构型及其有关参数进行了新的探讨和补充,同时比较了N3^-、N3、N3^+间相对稳定性和几何性质,并讨论了几种不同方法对该化合物系列诸性质参数的影响,结合MO理论及成键能的计算结果进行了成键分析。     

水葫芦、三七和菠菜光系统Ⅱ颗粒的分离及超快光谱 的研究

分离了三七、水葫芦和菠菜植物光系统Ⅱ富集的颗粒,并且采用吸收光谱和低温荧光光谱及皮秒荧光单光子计数技术进行了研究。结果显示,它们的吸收光谱图具有相似性。采用三指数动力学模型对三种光系统Ⅱ颗粒实验测定的光系统Ⅱ荧光衰减曲线拟合。水葫芦植物PSⅡ颗粒光系统三个组分荧光寿命分别是:157ps,415ps和1661ps;菠菜体系的相应荧光寿命分别是:198ps,677ps和1244ps;三七体系的相应荧光寿命分别是:14ps,272ps和184ps。慢速度荧光衰减由叶绿素堆积造成的,中等速度荧光衰减源于PSⅡ反应中心重新结合电荷组分,快速度荧光衰减归属于PSⅡ反应中心组分。基于20ps模型计算出三七植物PSⅡ颗粒的光系统Ⅱ反应中心转能效率为41%,水葫芦为89%,菠菜为91%,数值结果表明三七植物生长慢的特性可以表现在光合作用原初过程中,大量的被值物吸收的光子产生的激发态能量以荧光发射和非辐射形式消耗了,而没有被有效地利用,进一步验证了我们提出的观点：植物生长速度与它们的荧光性质和荧光寿命有相关性,生长慢的植物对激发态能利用效率则较低。     

适合倍频光波导的多层LB膜结构研究

制备非中心对称的NMOB/CdA交替Y型累积LB膜,测量了它的二阶非线性光学特性.为了改善多层膜的有序性,研究在拉制NMOB/CdA多层膜时提高膜均匀性的两种方法,增强了它的二阶非线性光学特性.最后,制备光栅耦合的NMOB/CdA多层膜光波导,测量了它的Cerenkov相位匹配光学二次谐波产生.     

Self-similar solutions for the anisotropic affine curve shortening problem

Similarity between the roles of the group on the equation for self-similar solutions of the anisotropic affine curve shortening problem and of the conformal group of on the Nirenberg problem for prescribed scalar curvature is explored. Sufficient conditions for the existence of affine self-similar curves are established. Received June 26, 1999 / Accepted January 28, 2000 / Published online December 8, 2000     

脉冲悬浮体进样火焰原子吸收光谱法直接测定土壤中铬

以阴离子表面活性剂SDS为增敏试剂,脉冲悬体进样火焰原子吸收光谱法直接测定土壤中格,结果表明,SDS在土壤悬浮体中对铬的吸收信号表现出明显的增敏作用,铬的绝对灵敏度为7．90ng(进样体积为500ul),直接测定土壤中铬的检出限达4．3ng,加标回收率99．4％,相对标准偏差3％（n=3),方法可直接测定NBS标准物质蕃茄叶中铬。     

A Novel Method for Synthesis of ZSM‐5 Coatings on Monolithic Cordierite Substrate

ZSM‐5 coatings, have been synthesized onto a monolithic cordierite substrate by an environmental friendly and high coating selectivity method—Vapor Phase Transport (VPT). With this method, an aluminosilicate gel coated onto the monolithic cordierite substrate has been transformed into a ZSM‐5 layer under vapors of n‐butylamine and water, n‐Butylamine played a key role in the forming of ZSM‐5 layer on the cordierite substrate. The ZSM‐5/cordierite monolith composites prepared by this method were ion‐exchanged with Cu²⁺ and tested for the selective catalytic reduction of NO by propane. The deNO_x activities of Cu/ZSM‐5 monolith catalysts were not only dependent on the ion‐exchange methods, but also on the ZSM‐5 loading of the monolith catalysts. The best result was obtained over the Cu (B3)/ZSM‐5 monolith catalyst, which had a ZSM‐5 loading of about 13% and was prepared by a pressure exchange procedure. At a temperature of 723 K and a space velocity of 10,000 h^?1 (based on the monolith volume), 85% of NO conversion and 93% of C₃H₃ conversion were achieved over the Cu(B3)/ZSM‐5 monolith catalyst.     

旋光性聚合物的铁电性能

旋光性高分子在结构上具有一定的空间特异性,因而可以有多种应用。根据铁电材料所必需具备的条件,经过特定的分子结构设计,可以使之具备铁电性能,据此,人们已合成了许多不同类型的铁电聚合物。本文按照铁电聚合物所处的聚集态不同,分别综述了具有铁电特性的晶态和液晶态旋光性聚合物的种类、结构特点及其铁电性能,分析讨论了影响液晶态旋光性聚合物的自发极化率和响应时间的因素。     

空气等离子法处理超高分子量聚乙烯纤维

用空气等离子法对高分子量聚乙烯纤维进行了表面处理,利用1,1－二苯基,二－苦基肼检测纤维表面自由基的产生、变化,并用亚甲基蓝、XPS表面元素分析、SEM等方法了纤维表面性能处理前后的变化。实验发现通过等离子离子处理后,纤维复合材料的剪强度从未处理的5．98MPa提高到了18．1MPa。     

Characterization of the copper-sulfur chromophores in nitrous oxide reductase by resonance raman spectroscopy: evidence for sulfur coordination in the catalytic cluster.

Nitrous oxide reductase (N(2)OR) from Pseudomonas stutzeri, a dimeric enzyme with a canonical metal ion content of at least six Cu ions per subunit, contains two types of multinuclear copper sites: Cu(A) and Cu(Z). An electron-transfer role for the dinuclear Cu(A) site is indicated based on its similarity to the Cu(A) site in cytochrome c oxidase (CcO), a dicysteinate-bridged, mixed-valence cluster. The Cu(Z) site is the catalytic site, which had long been thought to have novel spectroscopic properties. However, the low-energy electronic transitions and resonance Raman features attributable to Cu(Z) have been difficult to reconcile with a lack of conserved cysteine residues in standard alignments of N(2)OR sequences, other than those associated with the Cu(A) site. Recent evidence indicates that nitrous oxide reductase contains acid-labile sulfide and that this sulfide is a constituent of the Cu(Z) site (Rasmussen, T.; Berks, B. C.; Sanders-Loehr, J.; Dooley, D. M.; Zumft, W. G.; Thomson, A. J. Biochemistry 2000, 39, 12753-12756). We have used resonance Raman (RR) spectroscopy to selectively probe the Cu(A) and Cu(Z) sites of N(2)OR in three oxidation states (oxidized, semireduced, and reduced) as well as Cu(A)-only and Cu(Z)-only variants. The Cu(A) (mixed-valence, also designated as A(mv)) RR spectrum exhibits 10 vibrational modes between 220 and 410 cm(-1), with >1-cm(-1) (34)S isotope shifts that sum to -16.6 cm(-1). Many of these modes are also sensitive to (65)Cu and (15)N(His) and, thus, can be assigned to coupling of the Cu-S stretch, nu(Cu-S), with cysteine and histidine vibrations of the Cu(2)Cys(2)His(2) core. The RR spectrum of the Cu(Z) site (Z(ox)) reveals a novel Cu-sulfur chromophore with four S isotope-sensitive modes at 293, 347, 352, and 408 cm(-1), with a total (34)S shift of -19.9 cm(-)(1). The magnitude of the S isotope shifts and wide spread of perturbed frequencies are similar to those observed in Cu(A) and therefore suggest a sulfur-bridged cluster in Z(ox). The Z(ox) site has its nu(Cu-S)-containing modes at higher energy and exhibits less mixing with ligand deformations, compared to Cu(A). Reduction by dithionite produces a mixed-valence Cu(Z) site (Z(mv)) with six S isotope-sensitive RR modes between 282 and 382 cm(-1) and a total (34)S-shift of -16.9 cm(-1). The observation of a nearly identical RR spectrum in the C622D variant of N(2)OR, which lacks one of the conserved Cu(A) Cys residues, establishes that Cu-S vibrations observed in this variant arise from the Z(mv) site. Furthermore, none of the features assigned to Cu(Z) are detected in a second variant that contains only Cu(A). Therefore the resonance Raman spectra reported here provide compelling evidence for a unique Cu-S cluster in the catalytic site of nitrous oxide reductase.