广义簇合物在非均匀几率密度下的生长

采用族合物生长的自调整模型，并用扩散粒子的非均匀几率密度场模拟了簇合物和扩散粒子之间的非均匀相互作用势场,研究了广义簇合物在非均匀场下的生长形态，考察了深度因子α、粘附参数t等对簇合物生长形态及对非均匀场的影响，结果表明，非均匀场的性质是决定族合物生长几何形态的主要因素，深度因子α决定了簇合物中生长形态的紧密程度，粘附参数t决定了致密程度，α、t等参数对场的作用有一定的影响     

「VS_4-Cu_n」簇合物的固相合成、结构规律和成簇机理的研究

以(NH_4)_3VS_4为起始原料与CuCl在低温团相不同反应条件下,得到了不同簇骼的[VS_4-CU_n]的簇合物,并总结了CuCl/(NH_4)_3VS_4不同摩尔比、不同反应温度和时间对簇合物生成的影响和[VS_4-Cu_n]簇合物的结构规律.同时探索了V-Cu-S簇合物固相合成的成簇机理.     

多元多金属含氧簇合物

多金属含氧簇合物是一大类具有独特结构和特殊性能的化合物，对于基础理论研究和实际应用均有重要意义，其中多元多金属含氧簇合物的重要性日益渐增，本文拟对多元多金属含氧簇合物的结构，性能和制备作扼要的评述。     

钢表面彩色Mo-S-Fe簇合物膜

研究MoS₄^2-在钢表面发生配位化学反应所形成的具有装饰效果的多种彩色簇合物膜。FT-IR、F-IR、FT-Raman、 XPS和AES分析表明簇合物膜由Fe、Mo、 S、 O元素组成,在膜表面铁以Fe(Ⅲ)、钼以Mo(Ⅵ)状态存在,而在膜内层以Fe(Ⅱ)、Mo(Ⅳ)和Mo(Ⅵ)共存,S和O都呈-2价。从AES深度分布曲线的组成恒定区求得了各元素的相对原子百分浓度和膜层厚度,反应时间越长,膜越厚,膜为多分子层结构。     

大核镉硫簇合物的研究：（Ⅱ）两个八核镉在充簇合物的合成与晶体结构

利用ＣＳ２与镉硫化合物在溶剂中反应产生Ｓ＾２－来合成大核镉硫簇合物，得到了两个新的大核镉硫簇合物，并测定了其晶体结构，化合物（Ⅰ）为（Ｍｅ４Ｎ）２［ＳＣｄ８（ＳＰｈ）１２Ｃｌ４］，晶体属立方晶系，空间群Ｐａ３，ａ＝２６．７８２（３）Ａ，Ｖ＝１９２１１（４）Ａ＾３，Ｄｃ＝１．７５０ｇ／ｃｍ＾３，Ｚ＝８．１６３７个衍射点参与修正，Ｒ＝６．９６％，化合物（Ⅱ）为［Ｃｄ（Ｈ２Ｏ）６］［ＳＣｄ８（ＳＰｈ）１     

钼铁钴硫簇合物催化乙炔还原性质的研究

钼铁钴硫簇合物催化乙炔还原性质的研究①南玉明②（大庆石油学院石化系，安达１５１４００）徐吉庆蔡辉（吉林大学化学系，长春１３００２３）关键词簇合物类立方烷结构催化电化学性质在化学模拟生物固氮研究的推动下，人们已合成了上百种Ｍｏ－Ｆｅ－Ｓ簇合物，并研究了...     

硼烷簇合物的结构规则

从超额电子数出发，提出了1种稠合型硼烷的结构规则，讨论了各种规则间的关系。     

取代型钒氧簇合物

钒氧簇是多金属氧簇的一个重要分支.由于钒氧簇具有多样的结构、优良的物理特性,使得其在催化、磁性及光学材料等方面具有广阔的应用前景,引起了人们的日益关注.将主族的金属或非金属元素引入到钒氧簇体系,可以形成结构新颖的取代型钒氧簇.新颖构型及其拓展结构取代型钒氧簇合物的合成,极大地丰富了钒氧簇的结构类型,推动了钒氧簇合成化学...     

均匀电场对冰晶结构及生长的影响

采用分子动力学模拟方法研究了强度为4.0-40.0 V·nm^-1的均匀电场对过冷水冰晶结构和冰晶生长速率的影响. 文中通过CHILL 算法来识别不同的冰相结构,通过拟合Avrami 公式来得到冰晶生长所需的特征时间. 结果表明,在所施加的电场强度范围内生成的冰相以立方冰为主. 随着电场强度的增加,形成的立方冰的变形程度逐渐增大,冰晶的密度从0.98 g·cm^-3 增加到1.08 g·cm^-3,同时冰晶生长的特征时间从5.153 ns 减小到0.254 ns,冰晶生长的速率逐渐增长. 对水分子的动力学分析表明,冰晶生长速率增加的部分原因是电场能够促进水分子运动到形成冰晶所需要的取向. 此外,对冰相分子形成过程的分析表明缺陷冰分子在冰晶的生长过程中扮演着中间态的角色. 随电场强度的增加,由缺陷冰转变为立方冰的比例增长的速率逐渐提高.     

均匀电场对冰晶结构及生长的影响

Homogeneous crystallization of supercooled water under electric field with strength ranging from 4.0 to 40.0 V·nm^-1 was investigated by using molecular simulation technique. The liquid-solid transition was successfully obtained based on ice component analysis using the CHILL algorithm. The analysis suggested that the produced crystalline was cubic ice dominant. The influence of the field strength on the structure and the growth rate of the ice was studied. The results revealed that the presence of an electric field drove the system to crystallize rapidly into dense and distorted cubic ice. The density of the crystals increased as a function of the field strength, from 0.98 to 1.08 g·cm^-3. The growth rate of the ice nucleus increased along with the field strength according to the characteristic time derived from the Avrami equation which ranged from 0.254 to 5.513 ns. This type of acceleration can be partially attributed to the enhancement of the rotational dynamics of the water molecules. Moreover, by monitoring the formation history of the cubic ice, we found that the defective ice acted as a transition state linking the liquid water and the cubic ice.     

Precipitation Under Homogeneous or Heterogeneous Conditions by Photochemical Action

Abstract

Precipitation reagents may be formed in situ by photochemistry but the formation cannot be completely homogeneous due to the exponential nature of light absorption (Beer's Law). By proper adjustment of concentrations, one may vary the conditions from near homogeneous to heterogeneous formation of photoprecipitate.     

Inhomogeneous Electron Liquid in a Homogeneous Magnetic Field of Arbitrary Strength

Abstract

Our recent paper [Phys. Rev. A, 60, 2853 (1999)] on the field dependence of the energy of a molecule in an arbitrary magnetic field is extended here by results which can be expressed solely in terms of the total kinetic energy of the electron liquid of a molecule or an atom in a homogeneous magnetic field.     

氮化铝纳米锥的低温生长与场发射性能

考察了在600℃以下通过反应AlCl³+NH₃→AlN+3HCl制备AlN纳米锥的规律,结果表明在500℃时仍可获得AlN纳米锥,当温度为480℃时则无氮化物生成。场发射测试显示在500~600℃温区内制得的AlN纳米锥的开启电场处于14.2~20V·μm^-1范围,且随制备温度升高而减小。本工作的结果表明AlN纳米锥可在低温条件下获得,且具有较好的场发射性能。     

氮化铝纳米锥的低温生长与场发射性能(英文)

考察了在600℃以下通过反应AlCl3+NH3→AlN+3HCl制备AlN纳米锥的规律,结果表明在500℃时仍可获得AlN纳米锥,当温度为480℃时则无氮化物生成。场发射测试显示在500~600℃温区内制得的AlN纳米锥的开启电场处于14.2~20 V·μm-1范围,且随制备温度升高而减小。结果表明AlN纳米锥可在低温条件下获得,且具有较好的场发射性能。     

Homogeneous mono-and bimetallic catalysts for the oxidation of cyclohexene

In the absence of solvent, the first-row transition-metal acetylacetonate complexes and RuCl₂(PPh₃)₃ give fairly high turnovers for the allylic oxidation of cyclohexene under atmospheric pressure of oxygen. Synergetic effect is observed for the oxidation of cyclohexene by using M(acac)_n−RuCl₂(PPh₃)₃ bimetallic catalysts.     

Homogeneous catalytic hydrogenation of diethyland biphenyl-acetylene and isomerization ofCis-Stilbene in the presence of [(C5H5)2Ru3(CO)3(μ-CO)(μ3-CO)(C2Ph2)]

The title complex (1) is a good hydrogenation catalyst tar diphenylacetylene in homogeneous conditions; it comparison with the activity of other ruthenium clusters is made. Apparently cluster catalysis occurs, but fragmentation to binuclear metallacyclic products containing two alkyne molecules was also observed: these 40 not been previously described and have been characterized by elemental analyses and mass spectrometry. Complex1 contains all alkyne bound parallel to one metal-metal edge. The results obtained support the hypothesis that transition metal clusters with alkynes bound in this fashion could ad as catalysts precursors or as intermediates in the homogeneous hydrogenation of alkynes; this behavior would be an example of structure-reactivity relationship in homogeneous catalysis. An erratum to this article is available at .     

Homogeneous pyrolysis kinetics of ethyl 3-hydroxy-3-methylbutanoate in the gas phase

The pyrolysis kinetics of ethyl 3-hydroxy-3-methylbutanoate have been examined over the temperature range of 286–330°C and pressure range of 29–108 Torr. In a seasoned vessel and in the presence of the free radical inhibitor cyclohexene or toluene the reaction is homogeneous, unimolecular and obeys a first-order rate law. The elimination products are mainly acetone and ethyl acetate, and very small amounts of ethyl 3-butenoate, acetic acid, ethylene and H₂O. The rate coefficient is expressed by the following equation: log k₁(s^–1)=(12.39±0.46)–(174.5±5.2) kJ mol^–1 (2.303RT)^–1. The mechanism appears to proceed via a six-membered cyclic transition state, where polarization of the (CH₃)C(OH)^+...-CH₂COOCH₂CH₃ bond is rate determining.