金-硫团簇负离子组成特征的探讨

报导了金/硫靶在静态二次离子质谱实验条件下形成的组成通式为Au1－15S0－5的团簇负离子.其中,Aun组成系列具有典型的奇数优势,属于金的一元团簇负离子.其余组成系列（Au1－15S1－5）则属于金 硫二元团簇负离子.研究发现,金 硫团簇负离子具有以下与组成密切相关的特征: （1）它们继承了金一元团簇负离子的奇数优势;（2）它们中硫原子数仅限于5,而金原子数则在较大范围变化;（3）它们完全没有多数其它金属与非金属（包括硫）二元团簇正/负离子共有的MenNn型组成优势;（4）它们以上组成特征及其它细节恰似碳 磷这样的典型非金属二元团簇正/负离子.基于这样的组成特征可提出,金 硫团簇负离子在构成上包含着相对完整的金一元团簇组件,在形成机制上源于金一元团簇与硫一元团簇（或称为:限于五原子的多硫单元）之间的再团簇化.关于再团簇化机制中的相互作用问题,即两类团簇间是依靠末端原子交叉成键还是依赖两类团簇中异种原子之间静电诱导力等“非共价键”作用的问题,则有待于今后研究证实.     

激光蒸发产生钽钌酸铅团簇负离子的研究

激光蒸发产生钽钌酸铅团簇负离子的研究巨新，杨建红，施朝淑，张南，高振，孔繁敖，朱起鹤（中国科学技术大学，合肥，２３００２６）（中国科学院化学研究所，北京）关键词团簇离子，激光蒸发，奇偶性厚膜电阻以ＲｕＯ２、Ｐｂ２Ｒｕ２Ｏ７或Ｂｉ２Ｒｕ２Ｏ７作导电相，...     

氰化钾团簇的结构和形成机理研究

利用激光气化铁氰化钾或亚铁氰化钾并利用飞行时间质谱检测方法对氰化钾团簇的形成机理进行了研究，结果发现：团簇正离子可归属为［Ｋ（ＫＣＮ）＿ｎ］￣＋，ｎ＝０～３７，它们的幻数为ｎ＝４、１３、２２、３７；团族负离子可归属为［（ＫＣＮ）＿ｎＣＮ］￣－＝，ｎ＝０～１３，它们的幻数为ｎ＝４、１３。这些幻数与氯化钠等碱金属卤化物团簇体系完全一致。这表明：它们的团簇结构应该是相同的，即１×３×３（ｎ＝４）、３×３×３（ｎ＝１３）、３×３×５（ｎ＝２２）、３×５×５（ｎ＝３７）结构。因此氰化钾晶体的初期形成过程也应采取ＮａＣｌ型结构的增长途径。在激光气化产生的等离子体中，正、负离子与中性团簇的碰撞增长反应、正离子与负离子的复合反应以及团簇的亚稳态解离反应造成了团簇离子的不同丰度分布。氰化钾团簇中稳定立方体结构的产生决定了幻数的出现。     

气相中原子分子成簇动力学Ⅰ.动力学的基本模型

提出了气相原子、分子碰撞形成团簇的动力学一般模型，认为具有特定组份单元的粒子经碰撞后可任意组合成团簇．各缔合速率常数随团簇的尺寸和结构特征而变化．团簇的热解离速率主要取决于断键数．因此裂解出小碎片的几率较大．将上述模型用动力学方程表示，可计算在不同时刻的团簇尺寸分布．最后分析了激光烧蚀、电弧放电等几种形成团簇方法的具体条件．     

气相中原子分子成簇动力学 I. 动力学的基本模型

提出了气相原子，分子碰撞形成团簇的动力学一般模型，认为具有特定组分份单元的粒子经碰撞后可任意组合成团簇，各缔合速率常数随团簇的尺寸和结构特征而变化，团簇的热解离速率主要取决于断键数，因此裂解出小碎片的几率较大，将上述模型用动力学方程表示，可计算在不同时刻的团簇尺寸分布，最后分析了激光烧蚀，电弧放电等几种形成团簇的方法的具体条件。     

样品价态对激光气化产生Cu/Cl团簇的组成和稳定性的影响

研究团控的形成条件、形成机理是目前团簇科学中的一个热点领域［‘］．产生气相团簇的方法主要有Knudsen高温炉扩散法、粒子溅射法、激光气化／分子束法、直接激光气化法·因为不需要另加缓冲气体，直接激光气化法【刀具有对体系真空要求较低，装置简单，容易和飞行时间质谱结     

锗分族元素二元团簇及其与Co形成的团簇离子

通过比较激光烧蚀E1/E2 (代表Ge/Sn， Ge/Pb和Sn/Pb) 和Co/E (E为Ge、Sn、Pb)混合样品形成的二元团簇负离子飞行时间质谱分布和谱峰的相对强度及形成的幻数团簇离子峰，发现E1/E2二元团簇离子中原子量大的锗分族元素在团簇离子中占主要组分，而原子量小的元素则少量掺杂，其组成和分布特点说明其结构和性质与纯E团簇离子相似，可能的结构为该类负离子团簇所有原子都在笼结构的骨架上；对于二元团簇离子GeSn9－、GePb9－和SnPb9－其结构可能是双帽反四棱柱构型，只是每个原子均为骨架的一部分.而对激光烧蚀过渡金属钴与锗分族元素的混合物的研究发现，反应形成了丰富的Co/E二元合金团簇负离子，分析发现该类簇离子为钴内包覆于E(锗分族元素)笼状结构.幻数离子CoGe10－、CoSn10－和CoPb10－可能具有双帽四角反棱柱结构，而CoPb12－可能具有二十面体构型，钴原子均为笼状结构的中心.     

银硫团簇离子的形成与光解

银硫团簇离子的形成与光解于忠德，高振，张南，朱起鹤，孔繁敖（中国科学院化学研究所分子反应动力学国家重点实验室，北京１０００８０）本文首次报道用激光溅射方法产生了银硫团簇离子，并研究了部分团簇离子的紫外激光解离规律。由于银与铜都是具有满壳层ｄ电子结构的...     

激光溅射法生成金属掺杂氮原子团簇CuNn 、ZnNn 和ScNn

以高纯氮气为载气,通过激光分别轰击Cu/BN、Zn/BN和Sc/BN压制成的样品,首次生成了相应团簇CuNn 、ZnNn 和ScNn ,得到了团簇质谱图,确定了CuNn 、ZnNn 和ScNn 团簇中最稳定的组成分别为CuN4 、ZnN6 和ScN12 。     

银和硫团簇的反应

研究气相中原子或团簇的化学反应可以使我们从分子水平上研究化学反应的机理．激光溅射固体样品产生团簇,进而研究所形成团族的化学反应是研究团簇反应的一种方法．用高强度激光使固体样品气化,气化物彼此碰撞反应并在真空中膨胀冷却形成团簇和团簇离子,这一类反应是成...     

Substrate-induced Raman frequency variation for single-walled carbon nanotubes

We report on the monotonic Raman frequency shift and intensity variation when a laser spot moves along the same single-walled carbon nanotube (SWNT) for both the radial-breathing mode (RBM) and the G-band. Our substrates are Si wafers coated with thermal oxide, and trenches with widths of 1-80 mum are etched in the SiO2 by photolithography and reactive ion etching. SWNTs are grown by chemical vapor deposition and lie on top of the SiO2 and across the trenches. When the laser spot moves from the middle of the trench to the SiO2 region along the nanotube, we observe a clear upshift in the RBM and G-band frequencies and a decrease of intensity. The effect is more significant with large ( approximately 2 nm) diameter nanotubes and appears to be chirality dependent. These studies provide important information about environmental effects on single-walled carbon nanotube resonant Raman spectroscopy.     

pH-Responsive hollow polymeric microspheres and concentric hollow silica microspheres from silica-polymer core-shell microspheres

Nearly monodispersed silica-poly(methacrylic acid) (SiO 2-PMAA) core-shell microspheres were synthesized by distillation-precipitation polymerization from 3-(trimethoxysilyl)propylmethacrylate-silica (SiO 2-MPS) particle templates. SiO 2-PMAA-SiO 2 trilayer hybrid microspheres were subsequently prepared by coating of an outer layer of SiO 2 on the SiO 2-PMAA core-shell microspheres in a sol-gel process. pH-Responsive PMAA hollow microspheres with flexible (deformable) shells were obtained after selective removal of the inorganic SiO 2 core from the SiO 2-PMAA core-shell microspheres by HF etching. The pH-responsive properties of the PMAA hollow microspheres were investigated by dynamic laser scattering (DLS). On the other hand, concentric and rigid hollow silica microspheres were prepared by selective removal of the PMAA interlayer from the SiO 2-PMAA-SiO 2 trilayer hybrid microspheres during calcination. The hybrid composite microspheres, pH-sensitive hollow microspheres, and concentric hollow silica microspheres were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray (EDX) analysis.     

激光烧蚀硅酸盐的材料产生氧化硅氧化铝复合团簇

采用习飞行时间质谱技术,用308nm准分子激光烧蚀不同硅铝比的ZSM-5沸石,产生了氧化硅氧化铝复合团簇.在负离子通道测得含铝的新团簇系列[(SiO~2)~n~-~1(ALO~2)]^-和[(SiO~2)~nOAl]^-,讨论了这些系列的丰度分布和样品硅铝比之间的关系.由于AlO~2有较高电负性,激光烧蚀产生的团簇负离子系列[(SiO~2)~n~-~1(AlO~2)]^-具有以AlO~2为生长核心的生长机理。     

Characterization of silsesquioxanes by size-exclusion chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Liquid chromatography in combination with spectroscopic methods like matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) or nuclear magnetic resonance (NMR) spectroscopy is a powerful method to characterize silsesquioxanes and silsesquioxane mixtures. As new examples, the formation of silsesquioxyl-substituted silsesquioxanes [(n-octyl)(7)(SiO(1.5))(8)](2)O and [(n-octyl)(7)(SiO(1.5))(8)O](2)[(n-octyl)(6)(SiO(1.5))(8)] as well as the cage rearrangement of octa-[(n-heptyl)silsesquioxane] to larger structures [(n-heptyl)SiO(1.5))](n) up to n=28 are shown.     

浊度法快速评价胶体电池的灌胶均匀性

利用激光散射技术考察了分散体系的浊度T与分散相气相SiO2含量m的关系,结果表明T与m数值满足线性关系,拟合得到工作曲线关系式为m=T/62.44,在此基础上建立了浊度法快速测定气相SiO2含量的方法.利用浊度法求得模拟胶体电池隔板上电解液中SiO2的含量m0与理论值相吻合,进一步测定得真实解剖胶体电池的隔板内电解液中SiO2含量m0值也与理论值相吻合,证明了浊度法可以用来快速评价胶体电解液在电池内灌注均匀性.     

纳米级二氧化硅微球在三聚氰胺甲醛树脂上的微米化组装包覆

通过溶胶-凝胶法制得平均粒径为226 nm形状规整的球形二氧化硅微球.用硅烷偶联剂KH-570作表面处理后,使用十二烷基硫酸钠作为乳化剂,采用超声化学的方法,将纳米级二氧化硅组装包覆在三聚氰胺甲醛树脂表面,形成具有高比表面积的微米级颗粒.通过红外光谱FT-IR、扫描电子显微镜、激光粒度测试等方法对二氧化硅及组装颗粒进行表征,并对合成机理进行分析.发现二氧化硅在三聚氰胺甲醛树脂颗粒上均匀包覆,最后包覆物粒径分布较均一,平均粒径为30 μm.     

Novel structures and energy spectra of hydroxylated (SiO2)8-based clusters: searching for the magic (SiO2)8O2H3- cluster

The prominent (SiO(2))(8)O(2)H(3) (-) mass peak resulting from the laser ablation of hydroxylated silica, attributed to magic cluster formation, is investigated employing global optimization with a dedicated interatomic potential and density functional calculations. The low-energy spectra of cluster isomers are calculated for the closed shell clusters: (SiO(2))(8)OH(-) and (SiO(2))(8)O(2)H(3) (-) giving the likely global minima in each case. Based upon our calculated cluster structures and energetics, and further on the known experimental details, it is proposed that the abundant formation of (SiO(2))(8)O(2)H(3) (-) clusters is largely dependent on the high stability of the (SiO(2))(8)OH(-) ground state cluster. Both the (SiO(2))(8)O(2)H(3) (-) and (SiO(2))(8)OH(-) ground state clusters are found to exhibit cagelike structures with the latter containing a particularly unusual tetrahedrally four-coordinated oxygen center not observed before in either bulk silica or silica clusters. The bare ground state (SiO(2))(8)O(2-) cluster ion core is also found to have four tetrahedrally symmetric Si==O terminations making it a possible candidate, when combined with suitable cations, for extended cluster-based structures/materials.     

气相SiO2在不同pH值介质中的分散特性

以激光动态光散射法考察了气相SiO2在不同pH值的H2SO4和NaOH介质中的分散平均水化粒径与表面Zeta电位及二者间的关系。 Zeta电位数据表明，气相SiO2在水中分散的表面硅羟基的等电点(IEP)和滴定终点(TE)的pH值分别为pH(IEP)=2.09和pH(TE)=7.47，利用滴定终点pH (TE)给出了一种简单的气相SiO2表面Si-OH浓度的测定方法。 分散相粒径数据显示，在等电点和滴定终点之间，气相SiO2在水中的分散粒子的粒径能够稳定在230 nm附近；在H2SO4介质中，当pH＜pH(IEP)时，随着H2SO4浓度的增大，体系中的分散粒子发生聚结而使表观粒径增大；在NaOH介质中，当pH＞pH(TE)时，随着NaOH浓度的增大，分散相的表观水化粒径降低，表明NaOH的加入有利于气相SiO2的分散。     

Bare silica nanoparticles as concentrating and affinity probes for rapid analysis of aminothiols, lysozyme and peptide mixtures using atmospheric-pressure matrix-assisted laser desorption/ionization ion trap and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

The analysis of peptide mixtures from urine and plasma samples using bare (uncapped) SiO2 nanoparticles (NPs) with atmospheric-pressure matrix-assisted laser desorption/ionization mass spectrometry (AP-MALDI-MS) has been reported. The method was based on the adsorption of positively charged peptides on the surface of negatively charged SiO2 NPs through the electrostatic force of attraction. The adsorption on the surface of SiO2 NPs caused enhancement of ionization efficiency of analytes and subsequently increased the signal intensity of peptides. Maximum signal intensity was obtained at optimized concentration of SiO2 NPs and pH of the aqueous solution. The limits of detection (LODs) obtained for different peptides in deionized water with and without using SiO2 NPs were in the range 4.7-360 nM and 0.1-18.0 microM, respectively. The sensitivity of the proposed method was 21-53-fold better than conventional use of AP-MALDI-MS. In addition, linearity in the range 9.5-95 nM was obtained for the peptide angiotensin-II in deionized water with a correlation of estimation of 0.992 using an internal standard. The proposed method provided a simple way to facilitate the ionization of peptides, reduce sample complexity and increase the tolerance to salts and surfactants in the analysis of biological samples. The applicability of the present method was also demonstrated in the real-world sample analysis of aminothiols and lysozyme using MALDI-time-of-flight (TOF)-MS.     

Measurements of interface stress of silicon dioxide in contact with water-phenol mixtures by bending of microcantilevers

We use the bending of silicon microcantilevers to measure changes in mechanical stress at interfaces between phenol-water mixtures and SiO(2). The curvature of the microcantilever is measured by an optical system that combines a rapidly scanning laser beam, a position-sensitive detector, and lock-in detection to achieve a long-time stability on the order of 6 mN m(-1) over 4 h and a short-time sensitivity of better than 1 mN m(-1). Thermally oxidized Si shows the smallest changes in interface stress as a function of phenol concentration in water. For hydrophilic SiO(2) prepared by chemical treatment, the change in interface stress at 5 wt % phenol in water is larger than that of thermally oxidized Si by -60 mN m(-1); for SiO(2) formed by exposure of the silicon microcantilever to ozone, the change in surface stress is larger than that of thermally oxidized Si by -330 mN m(-1).