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1.
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βijk的程序。研究了各种取代基在吩噻嗪的氮上取代后衍生物的结构和二阶非线性光学系数。结论是N上取代推电子基对增大二阶光学非线性有利, N上取代吸电子基对增大二阶光学非线性不利。扩大共轭范围对增大二阶光学非线性有利。对上述结果在微观上给予了解释。  相似文献   

2.
采用量子化学abinitio HF和半经验ZINDO-SOS方法计算了吡嗪及其衍生物的电子光谱和三阶非线性光学系数.结果表明,中心对称的吡嗪衍生物随着体系共轭链的增长,最大吸收谱线波长增大,前线轨道能级差减小,体系的三阶非线性光学系数增大;引入取代基后可改变其三阶非线性光学性质.在相同骨架中引入吸电子基团-NO2形成A-π-A共轭结构,其三阶非线性光学系数比引入供电子基-NH2的体系大.  相似文献   

3.
选取聚并苯、聚并吡啶和聚并吡嗪的 3种共振结构为基体 ,计算不同共轭单体齐聚物的结构及被取代后的聚合物二阶和三阶非线性光学系数 .结果表明 ,聚合物的二阶非线性光学系数与其单体相比有显著增大 ,被—NH2 和 NO2 取代后的聚并苯、聚并吡啶和聚并吡嗪的非线性光学系数又在聚合物的基础上进一步大幅度增加 ,有的增加 2~ 3个数量级 .在非取代的聚合物中 ,聚吡啶各种结构的二阶非线性光学系数均较大 ;取代聚合物中 ,单—NH2 和—NO2 取代的聚并苯 ,尤其是反式共振结构聚并苯的二位— NH2 和五位—NO2 取代结构的聚合物二阶非线性光学系数高达 3 .2 7× 1 0 - 2 7esu,说明这种— NH2 和 -NO2 取代后的聚并苯是一种很好的非线性光学材料 .  相似文献   

4.
在 AM1方法优化的几何结构基础上 ,用 INDO/CI-SOS方法深入探讨亚酞菁 (C2 4 H1 2 B1 Cl1 N6 )的硝基取代对体系的电子光谱和二阶非线性光学性质的影响 .结果表明 ,吸电子取代基和取代基的共轭链的增长对亚酞菁的分子结构和电子光谱的最大吸收峰影响很小 ,但对非线性光学性质都有较大影响 ,随着共轭链的增长 ,二阶非线性光学系数大幅度增强 .未被取代的亚酞菁的 β0 计算值与实验值十分相符 ,分别为-0 .73× 1 0 - 2 8和 -0 .70× 1 0 - 2 8esu,共轭链最长的硝基取代化合物 β0 值增大到 -1 .47× 1 0 - 2 8esu,增加约近1倍 .  相似文献   

5.
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   

6.
运用密度泛函理论B3LYP方法对8-羟基喹啉(银、铂)(AgQ、PtQ2)金属配合物及其衍生物的非线性光学性质进行理论计算研究. 结果表明: 引入取代基使铂配合物的最强吸收波长产生较大红移. 最低能量跃迁吸收来自最高占据分子轨道(HOMO)到最低空分子轨道(LUMO)的d→π*和π→π*跃迁, 属于金属配体电荷转移(MLCT)与配体配体电荷转移(LLCT). 金属银和铂掺杂8-羟基喹啉使其三阶非线性光学系数γ值明显增大, 并且在配合物上引入―Ph, ―PhOCH3, ―PhF2, ―PhF5基团将进一步增大γ值. 引入基团的供电子性越强, γ值增大的幅度越大, 引入基团的吸电子性越强, γ值增大的幅度越小.  相似文献   

7.
在SM1和ZINDO方法基础上,按完全态求和公式计算分子二阶非线性光学系数β(ijk)和三阶非线性光学系数γ(ijkl),并对含偶氛功能团的双快类衍生物的二阶、三阶非线性光学性质进行了系统的理论研究.即在基础上,在分子左端引入推电子基N(CH3)2,右端分别引入推电子基CH2OH、2,5-二氮-4-硫甲苯基,研究取代基变化时β、γ变化的规律.对计算结果所反映的规律性在微观上给予了解释.  相似文献   

8.
本文采用引入外场微扰的CNDO/S—CI方法,计算了一系列苯衍生物的分子二阶非线性光学系数,探讨了取代基的电子性质、取代位置及取代基数目对分子二阶非线性光学系数的影响.结果表明;取代基的供电能力越强,分子的二阶非线性光学系数越大.D,A对位二取代苯和1—D,2.4—A,A三取代苯具有较高的非线性光学效应,苯衍生物中取代基数目为3时分子具有最佳的非线性光学效应.文中还对上述结论给出了初步的理论解释.  相似文献   

9.
在AM1和INDA/CI方法的基础上,按完全态求和公式自编了计算二阶非线性光学系数β~ijh的程序,并对酚蓝系列分子,考察了苯环取代基变化及不同原子闭环对二阶光学非线性的影响.苯环上引入推电子基团对增大β有利,引入吸电子基团对增大β不利;闭环形成三环体系对增大β有利.对上述结果所反映的规律性在微观上进行了解释.  相似文献   

10.
有机非线性光学材料具有非共振系数大,响应时间短,光损伤阈值高等优点,是当前材料科学的重要前沿课题之一,[1-2].目前主要采用改变取代基性质和共轭长度等方法来优化非线性光学极化率和透光性之间的关系[3-4].本文设计了一种新的结构,即在共轭链上含有多个交替排列的供电基团(D)和吸电基团(A),运用量子化学方法研究了这种聚酰胺分子的结构,非线性光学性质和电子光谱,发现它们的非线性光学系数随链长增大,而电子吸收波段并不发生红移.  相似文献   

11.
以邻菲罗啉双酮和N,N-二(4-丁氧基苯基)氨基苯甲醛为原料,设计合成了光功能配体(L)及其钌配合物1,运用现代分析测试手段进行了表征。利用开/闭孔Z扫描技术测试了目标化合物的三阶非线性光学性质。结果表明,在近红外范围内钌配合物具有比配体更大的三阶非线性系数和双光子吸收截面。通过UV-Vis吸收光谱、荧光光谱、圆二色光谱和粘度实验,研究了配合物与小牛胸腺DNA结合特性。结果表明,配合物通过插入模式与DNA结合。因此,该新型钌配合物可以作为非线性光学材料应用于生物显影。  相似文献   

12.
We present a quantum-chemical analysis of the central metal ion's effect on first hyperpolarizabilities and two-photon absorption (TPA) cross sections at the infrared region of a series of push-pull porphyrins whose synthesis and NLO properties have been reported earlier (J. Am. Chem. Soc. 2005, 127, 9710). The molecular geometries are obtained via the B3LYP/6-31G(d,p) level optimization including SCRF/PCM approach, and the NLO and TPA properties are calculated with the ZINDO/CV method including solvent effects. It is found that the CT transition between the metal ion's d orbital and the macrocycle pi orbitals plays an important role on NLO and TPA properties of metal porphyrins. Our data suggest a new approach to enhance TPA properties of porphyrin materials. We also present a quantum-chemical analysis on porphyrin dimers and trimers to understand the relationship between structural and collective NLO properties. It has been observed that beta values can be improved about an order of magnitude and TPA properties can be enhanced by 2 orders of magnitude by the formation of a trimer. The importance of our results with respect to the design of photonic and photodynamic therapy materials have been discussed.  相似文献   

13.
Density functional theory (DFT) calculations have been carried out to investigate the switching of the second-order nonlinear optical (NLO) properties of η(5)-monocyclopentadienyliron(II) and ruthenium(II) model complexes presenting 5-(3-(thiophen-2-yl)benzo[c]thiophen-1-yl)thiophene-2-carbonitrile as a ligand. The switching properties were induced by redox means. Both oxidation and reduction stimulus have been considered, and calculations have been performed both for the complexes and for the free benzo[c]thiophene derivative ligand in order to elucidate the role played by the organometallic fragment on the second-order NLO properties of these complexes. B3LYP, CAM-B3LYP, and M06 functionals were used for our calculations. The results show some important structural changes upon oxidation/reduction that are accompanied by significant differences on the corresponding second-order NLO properties. TD-DFT calculations show that these differences on the second-order NLO response upon oxidation/reduction are due to a change in the charge transfer pattern, in which the organometallic iron and ruthenium moieties play an important role. The calculated static hyperpolarizabilities were found to be strongly functional dependent. CAM-B3LYP, however, seems to predict more reliable structural and optical data as well as hyperpolarizabilities when compared to experimental data. The use of this functional predicts that the studied complexes can be viewed as acting as redox second-order NLO switches, in particular using oxidation stimulus. The β(tot) value of one-electron oxidized species is at least ~8.3 times (for Ru complex) and ~5.5 times (for Fe complex) as large as that of its nonoxidized counterparts.  相似文献   

14.
15.
Two nonlinear optical (NLO) chromophores C1 and C2 based on dithienylethene were designed and synthesized as the ultraviolet NLO switches. The open/close behavior of C1 and C2 were investigated through the UV–vis spectra. Through quantum chemical calculations of the dipole moments, first and second hyperpolarizabilities, etc. we analyzed both opening and closure states of C1 and C2. The NLO switch ability of the chromophores were studied through monitoring of the SHG at the opening/closure states, which were performed under illumination of fourth harmonic generation of the nanosecond Nd:YAG laser (λ?=?266?nm). The obtained results indicated that the maximal SHG changes were observed at energy density equal to about 90?J/m2, and the samples C1, 2′ closure states possess significantly higher value of the second order susceptibility compared to the opening states. After switching off of the external UV light, the induced second order susceptibilities remain up to 150?h without a decrease, which indicated that the obtained chromophores have the potential application as the NLO switches applied in photonics.  相似文献   

16.
《Chemical physics letters》2006,417(1-3):277-281
Despite many advantages toward nonlinear optical (NLO) waveguide devices, NLO polymers have not been adopted successfully into practical wavelength converters due to their high absorption losses. Empirical and theoretical understandings about NLO susceptibility imply the fundamental trade-off between optical absorption and nonlinearity. Our theoretical analysis elucidates the effect of absorption losses on second-harmonic generation (SHG). We compare analytically maximum conversion efficiencies for several NLO polymers and found a convincing approach for the development of NLO polymers with the optimum combination of high optical nonlinearity and low material absorption, which leads us to realize efficient polymeric SHG devices.  相似文献   

17.
在 ZINDO方法基础上 ,按完全态求和 (SOS)公式编制了计算三阶非线性光学系数γijkl的程序 ,研究了多取代巴比妥酸系列衍生物分子的结构 ,光谱和三阶非线性光学系数 γ(- ω;- ω,ω,ω) ,γ(0 ;0 ,0 ,0 ) .除了通常的 D- π- A结构外 ,还研究了 D- A-D结构 .对这些 NL O生色团分子的结构与三阶 NLO性质的关系给予系统的理论研究 .考察了给体 ,桥 ,受体变化 ,D- π- A结构及 D- A- D结构对 γ的影响 ,结论是 :1 .氧代巴比妥酸受体三阶 NLO系数高于硫代巴比妥酸受体 . 2 .芳基给体取代基与烷基给体取代基相比 ,不仅热稳定性高于后者 ,而且 γ值亦高于后者 ,从而设计了一系列有实际应用价值的热稳定性好、有优良非线性光学性质的分子  相似文献   

18.
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:10,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   

19.
以γ 缩水甘油氧丙基三甲氧基硅烷 (KH5 6 0 )作中间体 ,用溶胶 凝胶 (Sol Gel)法合成了含对硝基偶氮苯胺 (DO3)生色团的新型键合型有机 /无机复合非线性光学 (NLO)材料 ,在这种有机生色团与无机玻璃键合形成的交联网络结构中 ,无机玻璃的刚性三维结构和优良的高温稳定性能有效抑制NLO生色团的极化松弛 .二次谐波信号 (SHG)测量表明 ,合成的键合型聚合物膜的二阶非线性光学系数 (d33)值达 5 79× 10 -7esu ,NLO稳定性也较好 ;在室温下放置 90天后 ,其d33 值能维持初始值的 93 5 % ;在 10 0℃下放置 30 0min后 ,其d33 值仍能维持初始值的 6 0 %  相似文献   

20.
The geometrical structures and stability of non-conjugated C5H10 and C3H8N2 singlet and triplet diradical molecules have been investigated at the UCCSD/6-311g** level. The effects of molecular structure, radical position, amount of Hartree Hork (HF) exchange and spin multiplicity on the nonlinear optical (NLO) coefficients have been also investigated. The reliable UCCSD results show that the triplets of all diradical molecules are more stable compared to their singlet analogues. In addition, the α s and β tot values of C5H10 and C3H8N2 triplet diradical mo-lecules have been investigated by the UBHandHLYP, UB3LYP, UBLYP, UHF and UCCSD methods. The investigation shows that the variations in α s and β tot values are closely connected to the amount of HF exchange. The increasing amount of HF exchange results in monotonic decreases in α s and β tot values, while the α s and β totvalues of singlet diradical molecules and the γ s of C5H10 and C3H8N2 singlet and triplet diradical molecules have been studied by the UBHandHLYP method. The results illustrate that the NLO coefficients for our studied non-conjugated carbon and nitrogen diradical species can be tuned by molecular structure, radical position and spin multiplicity, which are very significant for designing NLO materials.  相似文献   

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