掺杂正八面体AgBr乳剂介电频谱的研究——Cd2+、Br-离子的影响

测定了单分散正八面体AgBr乳剂中加入不同量CdBr₂和KBr以后的介电吸收频谱。发现Cd²⁺离子的表面掺杂使正八面体AgBr乳剂的介电吸收峰向低频方向位移。这种变化在CdBr₂的加入量为0—2×10^-2mol/mol AgBr范围内尤为明显。说明掺杂Cd²⁺使正八面体AgBr乳剂中AgBr微晶的介电电导率σ₂显著下降。能进入AgBr微晶表面层晶格中的Cd²⁺离子的数量不仅与乳剂中Cd²⁺离子的浓度有关,而且与乳剂中的Br^-离子浓度有关。通过简单的水洗,可以将掺杂的Cd²⁺大部分除去。水洗后,样品的介电吸收峰又向高频方向回移。在本实验条件下,Cd²⁺离子掺杂的这种“可逆性”表明进入AgBr微晶中的Cd²⁺离子主要是处在AgBr微晶的表面层内。样品介电吸收峰频率位置的这种可逆变化表明:非均匀电介质中的界面极化效应在保持连续相不变时,受分散相颗粒表面层物质的组成和结构的影响很大。     

掺杂立方AgBr乳剂介电频谱的研究——Ⅲ.硫的影响

本文研究了用1×10^-5mol～1×10^-2mol Na₂S₂O₃/mol AgBr和1×10^-4mol～1×10^-2mol Na₂S/mol AgBr掺杂的立方AgBr乳剂的介电吸收频谱.发现在我们的实验条件下,当Na₂S₂O₃的加入量小于1×10^-4mol/mol AgBr时,Na₂S₂O₃,在AgBr微晶上吸附的影响占主要,样品介电吸收峰的f_max稍向低频方向位移,f_max位移量(△log f_max)的大小与AgBr微晶的表面状况有关.当Na₂S₂O₃的加入量大于1×10^-4mol/mol AgBr时,Na₂S₂O₃对AgBr微晶表面的溶蚀的影响逐渐占优势,使AgBr微晶表面的结构不均匀性增加,同时乳剂的pAg上升,结果样品的f_max逐渐向高频方向移动,介电吸收峰亦相应展宽.Na₂S的加入量小于1×10^-3mol/mol AgBr时,样品的f_max有稍向低频位移的趋势.当将掺Na₂S的样品干燥后在75℃和110℃下放置6小时后,f_max明显向高频方向移动.     

电子相互作用和高聚物中的极化子

各种电致发光聚合物具有非简并基态.当电子和空穴注入后,形成的载流子是极化子.极化子的大小和能量决定于电子相互作用.目前大家采用Hubbard model来描述聚合物中的电子相互作用,所得到的结果与实验不符.Hubbard model和extended Hubbard model对窄能带体系是好的近似,但聚合物是宽能带,反映价键关联的非对角相互作用（在extended Hubbard model中被略去）有重要贡献,特别是在强屏蔽情况下,价键关联与Hubbard关联相互竞争,可纠正现有理论的缺陷. 关键词：     

Synthesis and Crystal Structure of the Derivative of β-elemene C_(20)H_(33)N·Cl_3CCOOH

１ＩＮＴＲＯＤＵＣＴＩＯＮβ ｅｌｅｍｅｎｅ,ａｓｅｓｑｕｉｔｅｒｐｅｎｏｉｄｃｏｍｐｏｕｎｄ,ｉｓａｎａｔｕｒａｌｐｒｏｄｕｃｔｉｓｏｌａｔｅｄｆｒｏｍｅｓｅｎ ｔｉａｌｏｉｌｃｏｎｔａｉｎｅｄｉｎｔｈｅｒｏｏｔａｎｄｓｔｅｍｏｆＣｈｉｎｅｓｅｈｅ...     

Crystal Structure of[PrAl(CF3COO)2(CF3CHOO)(C2H5)2(C4H8O)2]2

[PrAl(CF3COO)2(CF3CHOO)(C2H5)2(C4H8O)2]2 Mr=1420.56, monoclinic, P21/n, a=10.651(6), b=24.276(9), c=11.110(5)(), β=107.650(4)°, V=2737.4(1)()3, Z=2, Dc=3.45 g/cm3, F(000)=2816, T=233K, MoKα radiation (λ=0.71069()), μ(MoKα)=38.017 cm-1, R=0.048 for 2847 observed reflections (I≥3σ(I)). It is isostructural with [LnAl(CF3COO)2(CF3CHOO)-R2(C4H8O)2]2 (Ln=Ho, R=Et; Ln=Nd, Y, R=iBu). Pr3+ is coordinated by eight oxygen atoms from five bridging ligands and two THF forming a distorted bicap-prism.     

Crystal Structure of 〔PrAl(CF_3COO)_2(CF_3CHOO)(C_2H_5)_2(C_4H_8O)_2〕_2

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Ca2B2O5的电子结构和能带结构

合成了标题化合物,在已测晶体结构的基础上,利用含组态作用的INDO/S方法计算了其他电子能带结构;利用态求和方法计算了微结构分子的线性极化率及其晶体的平均折射率。分析结果表明,价带主要由B^3^+和O^2^-离子的价轨道的贡献,导带底部主要由Ca^2^+离子轨道的贡献,从O^2^-离子到Ca^2^+离子的电荷转移对线性极化率起主要贡献。     

Photocatalytic reduction of dichromate by titanium dioxide supported on hollow glass microbeads

The photocatalytic reduction of dichromate using TiO2/beads as a photocatalyst was studied. The results showed that 3.8 × 10-4 mol/dm3 of dichromate can be completely reduced into Cr3 after illumination for 35 min with a 375 W medium pressure mercury lamp. The effects of factors such as the amount of TiO2/beads , initial concentration of dichromate, initial pH, nitrogen and oxygen atmosphere, and concentration of Fe3 on the photocatalytic reduction of dichromate were investigated. A possible mechamism of the photocatalytic reaction was proposed. After illumination for 200 h, no significant loss of photocatalytic activity of TiO2/beads was observed.     

Efficient Isomerization for Preparing thans-2,2-Dimethyl-3-(2,2-dichloroethenyl) cyclopropanecarbonyl Chloride

2,2-Dimethyl-3-(2,2-dichloroethecyclopropanecarbonylchloride(hereafterreferredtoaspermethricacidchloride)isausefulintermediateforthepreparationofsomesyntheticpyrethroids,suchaspermethrinandcypermethrin.Permethricacidchloridehasageometricalisomericpair,oiLyandtrans,owingtoitscyclopropanering.Itisknownthat,ingeneral,theestersderivedfromtheirans-isomerarelesstoxictomammalsthanthosederivedfromtheets-isomerl--3.Thepermethricacidproducedindustriallyisalwaysinformsofmixturesoftrans-andets-isomers.Ac…     

Synthesis of Asymmetric 4H-1, 3, 2-Benzodioxaphosphorin 2-Sulfides from Intramolecular Cyclization Reaction

Avarietyofbiologicalactivitiesofsome4H-l,3,2-benzodioxaphosphorin2-sulfideshavebeenreported,forexampletheinsecticideSalithionl.Thecyclicphosphonothionateshavebeenpreparedbyintermolecularcondensationofphosphorodichloridothioateswithsalicylalcoholoritsderivativesinthepresenceofabase=,andbyintramolecularcyclizationreactionofthesalicylalasthestartingmaterial3.However,theintramolecularcyclizationreactionofthe2-hydrobenzophenonesandstereochemicalstudieshavenotbeenreported.Wenowdescribeanewsynthesis…