首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 415 毫秒
1.
本文采用引入外场微扰的CNDO/S-CI方法,计算了一系列取代共轭多烯分子的二阶非线性光学系数β_(vec),探讨了取代基及共轭链长与分子微观非线性光学效应的关系和规律.结果表明:吸电子或供电子基团的引入,有利于增强分子的微观非线性光学效应,但该效应随取代基数目增多有减缓的趋势,“饱和”取代时由于“饱和效应”而使β_(vec)值降低;取代基间的距离增大,分子的β_(vec)值提高,端基取代时β_(vec)值最大;取代共轭多烯的lnβ_(vec)与分子中所含双键数n之间具有线性关系.本文还对上述结论给出了理论解释.  相似文献   

2.
运用密度泛函理论(DFT)的BP86方法, 对[M6Om(C25N4H18)n]2-(M=W, Mo; n=1, 2; m=17,18)进行了几何结构优化, 其中Mo系列结构化合物优化的几何结构与实验值吻合较好. 在净电场为零的条件下, 运用DFT/LB94方法计算了体系的二阶非线性光学系数β值: 体系1和2的βvec值分别为154.4×10-30和124.8×10-30 esu. 表明它们具有较大的二阶非线性光学系数, 且Mo系列比W系列的β值大. 而体系3和4的βvec值分别为218.0×10-30和191.8×10-30 esu. 体系3和4的βvec值分别比体系1和2的大, 表明增加给体的数目有利于提高NLO响应, 但都小于它们的2倍.  相似文献   

3.
2-苯基苯并咪唑衍生物非线性光学性质的从头算研究   总被引:7,自引:3,他引:7  
采用HF/6-31G^*方法优化分子构型,在此基础上用CPHF方法系统地研究了多种基团取代的2-苯基苯并咪唑衍生物的二阶非线性光学系数βvec,并对βvdc的影响因素进行了探讨,为进一步设计综合性能优良的有机非线性光学材料提供理论指导.  相似文献   

4.
采用密度泛函理论B3LYP/LANL2DZ方法,对实验合成的含有不同生色团的Pt(Ⅱ)配合物的电子性质和二阶非线性光学(NLO)效应进行计算分析。结果表明:配合物中二苯基啡咯啉部分表现出给电子的性质,金属Pt(Ⅱ)在配合物内起到平衡电荷的作用。对配合物lb~6b与配合物a进行比较发现,配合物1b-5b的βvec值比配合物a的成βvec值增大,而配合物6b的βvec值比配合物a的风值减小。7个配合物中前线分子轨道能级差越小的配合物,它的βvec值越大,同时配合物更深层占有轨道与空轨道之间的电子跃迁对二阶NLO效应有明显的贡献。  相似文献   

5.
氨基酸桥联手性双卟啉的二阶非线性光学性质研究   总被引:4,自引:0,他引:4  
采用半经验量子化学PM3方法对系列氨基酸桥联双卟啉1, 2, 3, 4及其锌配合物进行了几何结构优化, 并用TDHF/PM3方法计算了其静态二阶非线性光学系数. 计算结果表明, L型-氨基酸桥联双卟啉及其锌配合物具有右手螺旋结构特征. 在电偶极近似下, 不同手性氨基酸侧链基团R对分子的总体二阶非线性光学系数β和βHRS的影响不大, 但对二阶非线性光学系数的手性分量βxyz却有显著影响. βxyz与螺旋结构参数r2ζ/L4成正比关系, 符合手性分子二阶非线性光学响应的单电子螺旋模型理论. β张量分析表明, 此类分子表现为以八极为主、 偶极为辅的多极分子, 卟啉环与锌离子的配位有利于增加二阶非线性光学响应的偶极分量和手性分量βxyz.  相似文献   

6.
在ZINDO方法基础上,按完全态求和(SOS)公式编制了计算分子二阶非线性光学系数β的程序.研究了(4,5-二氮杂-9-亚芴基)碳60中的分子轨道相互作用,计算了该分子的电子光谱和二阶非线性光学系数,前者与实验结果较好地吻合,后者属于理论预测性质.  相似文献   

7.
以INDO/SCI方法为基础,按完全态求和(SOS)公式编制了计算分子二阶非线性光学系数β~i~j~k和β~μ的程序。研究了1,2-二氨基-4,5-二硝基苯1和其异构体1,3-二氨基-4,6-二硝基苯2的电子光谱和二阶非线性光学性质。计算表明分子1具有与分子2几乎相等的二阶非线性极化率。但由于分子1的偶极矩明显大于分子2的,故分子1的μβ值比分子2的μβ值大的多。在此基础上,研究了2,3-二(β-苯乙烯基)-5,6-二氰基吡嗪和2,3-二(β-噻吩乙烯基)-5,6-二氰基吡嗪和2,3-二(β-噻吩乙烯基)-5,6二氰基吡嗪衍生物的电子光谱和二阶非线性光学性质。结果表明,这些化合物均具有两个相距很近的强吸收峰,它们对β值的呈加和模式。由于这类化合物特征吸收峰均位于413nm以下且具有大的μβ值,所以,它们是一类很有前途的二阶非线性光学候选材料。  相似文献   

8.
硼羰基取代螺旋共轭化合物电子结构的理论研究   总被引:2,自引:2,他引:0  
在AM1方法优化的几何结构基础上,用INDO/CI-SOS方法深入探讨硼羰基(B—CO)螺旋共轭化合物的二阶非线性光学性质,讨论了硼羰基的不同取代位置对螺旋共轭体系的电子光谱、二阶非线性光学系数的影响.结果表明硼羰基的引入可改善体系的非线性光学性质,随着硼羰基个数的增加,二阶非线性光学系数增大,大入射波长为1064nm时,β绝对值比未被取代的螺旋共轭化合物的β值增大一个数量级,达到13 84×10-40C·m.  相似文献   

9.
采用量子化学PM3方法优化得到二联吡啶及四种二氮取代衍生物的稳定结构,利用ZINDO-SOS∥PM3方法对它们的二阶和三阶非线性光学性质进行计算.结果表明,该类化合物具有良好的非线性光学性质,其中1,6,1′,6′-四氮取代联苯的β值最大,为73 2082C·m,而2,4,2′,4′-四氮取代联苯的三阶非线性光学性质最显著.  相似文献   

10.
取代基间电荷转移对分子二阶非线性极化系数的影响   总被引:2,自引:9,他引:2  
计算了苯胺、硝基苯、邻硝基苯胺、间硝基苯胺、对硝基苯胺及2,4-二硝基苯胺的二阶非线性光学系数β_2,讨论了取代基间电荷转移对分子二阶非线性光学系数的影响。得知β′=β_(add)+β_(ct)不是很好的计算公式,但考虑取代基间的电荷转移对β的贡献仍有其价值。  相似文献   

11.
The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.  相似文献   

12.

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

  相似文献   

13.
非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。  相似文献   

14.
Two vanilloids, (5E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one (1) and 4-[3-hydroxydecyl]-2-methoxyphenol (2), isolated from the dried seeds of Grains of Paradise (Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared.  相似文献   

15.
针对恶臭测试的环境影响问题,提出了解决的实例方案,并对方案的要点及优缺点进行讨论,此方案在实际操作中具有较好的效果。  相似文献   

16.
In this review, the research of the author in the field of colloidal systems is summarized. The factors influencing colloidal stability are systematized and analyzed. Examples are presented to illustrate the practical utilization of the theory of stability of colloids and thin films.This review was prepared on the basis of the works of the author, which were awarded the State Premium for 1991 in the field of science and technology, chemistry section.Institute of Physical Chemistry, Russian Academy of Sciences, 117915 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1708–1717, August, 1992.  相似文献   

17.
Main hydration products of two cement pastes, i.e. CSH-gel, portlandite (P) (and specific surface S) were studied by static heating, and by SEM, TEM and XRD, as a function of cement strength (C-33 and C-43) hydration time (th) and subsequent hydration in water vapour.Total change in mass on hydration and air drying, Mo, increased with strength of cement paste and with hydration time. Content of water escaping at 110 to 220°C, defined as water bound with low energy, mainly interlayer and hydrate water, was independent on cement strength but its content increased with (th). Content of chemically bound (zeolitic) water in CSH-gel, escaping at 220-400°C, was slightly dependent on strength and increased with (th). It was possibly derived from the dehydroxylation of CSH-gel and AFm phase. Portlandite water, escaping at 400-500°C, was independent on cement strength and was higher on longer hydration. Large P crystals were formed in the weaker cement paste C-33. Smaller crystals were formed in C-43 but they increased with (th). Carbonate formated on contact with air (calcite, vaterite and aragonite), decomposed in cement at 600-700oC. It was high in pastes C-33(1 month) and C-43(1 month), i.e. 5.7 and 3.3%, respectively; it was less than 1% after 6 hydration months (low sensitivity to carbonation) in agreement with the XRD study showing carbonates in the air dry paste (1month), and its absence on prolonged hydration (6 months) and on acetone treatment. Water vapour treatment of (6 months) pastes or wetting-drying increased this sensitivity.Nanosized P-crystals, detected by TEM, could contribute to the cement strength; carbonate was observed on the rims of gel clusters.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

18.
袁丽秋 《化学教育》2006,27(5):8-10
面对日益枯竭的能源危机,氢能是一种洁净、最有前景的替代能源。目前在各种制氢的方法中光催化分解水制氢的研究最多,光解水过程中催化剂最关键,本文对利用太阳能光解水的途径、提高光催化反应效率以及光催化剂的开发研究进行了综述。  相似文献   

19.
20.
黄酮化合物的合成研究进展   总被引:2,自引:0,他引:2  
黄酮化合物是一类具有多种生物活性的天然产物,其经典的合成方法主要为查耳酮路线和β-丙二酮路线.近年来出现了许多新技术、新方法.本文介绍了2'-羟基查尔酮的氧化关环法、黄烷酮氧化法、改进的Baker-Venkataraman法及其他合成黄酮化合物的方法.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号