含IIIA或VA族杂原子的碳原子簇负离子的研究

在自制的仪器上，以脉冲激光束在高真空中溅射适当的样品，产生了一系列合有1个VA族原子（N、P、As）或ⅢA族原子（B、Al）及13个以下碳原子的原子簇负离子。在实验记录的飞行时间质谱中，这些簇离子的信号强度均因其碳原子数的奇偶而发生交替变化．对实验结果的分析研究显示：这些簇离子均为直链构型．VA或ⅢA族原子位于链的一端，所有成簇原子的价键均得到满足．     

铁、钴、镍/磷二元团簇离子的形成与光解

利用激光直接溅射法产生了铁、钴、镍／磷二元团簇正负离子,并用串级飞行时间质谱仪研究了团族离子的组份和激光光解规律,质谱研究表明,铁、钴、镍易与磷结合成簇,而且样品中磷含量的增加有助于大尺寸团簇离子的生成,当形成的团族簇离子中含金属原子数目较少时,磷原子数目可在较大范围内变动,其中ＭＰ２＾＋、ＭＰ４＾＋、Ｍ２Ｐ４＾＋（Ｍ＝Ｆｅ、Ｃｏ、Ｎｉ,ｎ＝２、３、４）团簇离子均具有较高的丰度;随着金属原子数目的     

结构光性矿物学研究——离子的电子壳层结构对矿物折射性质的影响

本文以Mandarino或作者给定的K值为基础,计算了格拉斯顿-代尔离子折射度(即GDIR值)。并对离子的电子壳层结构对矿物折射性质的影响作了讨论,得出了如下结论: 1.氖型结构离子的化合物折射率随其密度增加而线性地增加; 2.惰性气体型离子和18电子型离子的离子折射度有不同的变化规律; 3.周期表中ⅠA,ⅡA,ⅢA,ⅣA,ⅤA和ⅥA族的离子的折射度随原子序增加而线性地增加; 4.第一过渡族元素的离子折射度有双驼峰型的曲线; 5.由于镧系的收缩,稀土元素的离子折射度随原子序的增加而降低。     

硅、锗、锡、铅/磷二元原子团簇的形成、光解和结构

利用激光溅射产生了第IV主族 (硅、锗、锡、铅 ) /磷二元团簇正负离子 ,用飞行时间质谱研究了团簇离子的组成规律和激光光解产物 .研究表明二元团簇稳定性受团簇电子结构和几何结构的影响 ,但随着第IV主族元素自上而下 ,几何结构对团簇稳定性的作用越来越大 .在二元团簇离子中存在两类幻数团簇 :一类可以用Wade规则解释 ,其中磷原子或者充当给电子配体结合在第IV主族原子构成的团簇骨架外 ,或者直接参与团簇骨架的构成 ;另一类则与稳定的第IV主族中性团簇 (或磷中性团簇 )是等电子体 .利用从头计算和Wade规则对幻数团簇的结构和价键进行了分析 .     

硅与碳、磷、硫、氧的二元簇离子的激光产生

通过在自制仪器上发生的激光等离子体反应, 产生了硅与碳、磷、硫、氧等非金属元素形成的二元原子簇离子, 记录了它们的飞行时间质谱。根据对这些簇离子的组分的分析, 认为在硅碳簇离子中碳原子形成直链, 硅原子位于链端; 硅硫簇离子中的硅原子向一维伸展, 通过硫原子桥连一起; 硅磷簇离子则主要来取多面体的构型。所有成簇硅原子的价电子在各簇离子中都充分参于成键。     

AgnSm^±和AunSm^±的激光产生与质谱研究

以高能量密度的脉冲激光束在高真空中直接溅射银(金)粉与硫的混合物, 产生了丰富的银-硫和金-硫二元原子族正负离子, 记录了它们的飞行时间质谱。通过对这些簇离子的组成与分布的分析, 发现了它们的一些结构规律。银硫簇离子以离子键为主, Ag2S是它们的主要结构单元, 其中Ag11S5^+和Ag9S5^-特别稳定; 金硫簇离子基本上是共价结构, 金原子间相互成键, 构成簇离子的核, 硫原子则仅与核表面的金原子配位, 其中Ag6S14^+, Au5S6^-的稳定性比较突出。     

FT-ICRMS在团簇化学中的应用(Ⅱ)--第一过渡系金属离子与丙炔醇的吸附和反应

近10多年以来,金属离子及其团簇离子在气相中的吸附、催化和反应得到了广泛的关注.在去除溶剂化效应、离子对等干扰的条件下,一些金属有机化合物的反应活性及其催化机理得到了更本质的阐述[1-4].由于过渡金属元素因其外层价电子结构利于插入有机键,使其对大量的有机物都具有反应活性[5].我们探讨了第一过渡系金属离子与丙炔醇的吸附和反应[6].本文介绍利用傅利叶变换离子回旋共振质谱(FT-ICRMS)研究气相中第一过渡系金属离子与丙炔醇的吸附和反应,得到了一些有意义的结果,并讨论了其规律和机理.     

有机盐类化合物醋酸钠的电喷雾质谱研究

利用电喷雾质谱技术研究了有机盐类化合物醋酸钠(NaAc)的特征质谱行为,实验结果表明,在全扫描电喷雾正负离子谱中都出现了质量数相差82的质谱峰簇．这与醋酸钠的相对分子质量相一致,正负质谱峰簇分别对应于簇合物离子Na^ (NaAc)n和Ac^-(NaAc)m:簇合物离子的多级串联质谱进一步证明了簇合物离子的存在。该结果为类似结构的盐类化合物的表征提供了一种新的质谱证据。     

Pt2M2异金属四核原子簇化合物成键规律探讨

对十二个Ｐｔ２Ｍ２四核异金属簇化合物进行了量子化学ＤＶ－Ｘα方法的计算与讨论，探讨了这些原子簇的成键规律，它们大致可分为三类：Ｐｔ与Ⅷ族金属形成的四核簇，Ｐｔ尽量保持自己原有的价电荷；Ｐｔ与ⅥＢ族金属形成的原子簇，ⅥＢ族元素是电荷的主要提供者，Ｐｔ与ＩＢ族金属形成的原子族，体系主要由配体ＰＰｈ３提供电荷，并提出，簇合时，三苯基膦酸体起电子调节作用，环戊烯基配体起推电子作用，从能带分析，ⅥＢ族或ＩＢ     

吡啶团簇的飞秒光电离和从头计算研究

用飞秒激光电离飞行时间质谱研究了吡啶分子团簇在400 nm波长下的多光子光电离,实验观测到一系列的质子化和非质子化团簇离子.结果表明,质子转移也能发生在弱氢键结合的分子间.通过分析离子峰宽和离子信号强度随气源压力的变化,得到质子化团簇离子来源于大团簇离子的碎裂,而非质子化团簇离子是中性团簇直接电离的结果.从头计算结果表明,吡啶团簇是通过弱氢键C-H…N 结合在一起的,并且团簇离子离解倾向于生成质子化产物.     

Cun,Agn,Aun（n=2,3,4）原子簇结构的理论分析

在应用ＤＶ－Ｘａ自洽场方法研究Ｃｕｎ，Ａｇｎ，Ａｕｎ原子簇电子结构基础上，分析了原子簇中原子轨道间的相互作用及其大小随几何构型的变化，并讨论了原子簇的Ｘａ总能量与原子簇几何构型的关系，采用单、双过渡态理论方法分别计算原子簇分子轨道的电离能和分子轨道的电子跃迁能，结果表明Ａｇｎ的电离能计算值与实验值符合较好，而Ａｕｎ原子簇则有一定偏差，这可能是由Ａｕｎ的较大相论效应引起的，Ａｇ４的电子跃迁能与实验值     

Hydrogen bonding in phenol, water, and phenol-water clusters

Structure, stability, and hydrogen-bonding interaction in phenol, water, and phenol-water clusters have been investigated using ab initio and density functional theoretical (DFT) methods and using various topological features of electron density. Calculated interaction energies at MP2/6-31G level for clusters with similar hydrogen-bonding pattern reveal that intermolecular interaction in phenol clusters is slightly stronger than in water clusters. However, fusion of phenol and water clusters leads to stability that is akin to that of H(2)O clusters. The presence of hydrogen bond critical points (HBCP) and the values of rho(r(c)) and nabla(2)rho(r(c)) at the HBCPs provide an insight into the nature of closed shell interaction in hydrogen-bonded clusters. It is shown that the calculated values of total rho(r(c)) and nabla(2)rho(r(c)) of all the clusters vary linearly with the interaction energy.     

Polyanionic Clusters and Networks of the Early p-Element Metals in the Solid State: Beyond the Zintl Boundary

Reduction of p-element (post-transition) metals and metalloids by alkali metals leads to many salts containing polyatomic clusters or network anions of these elements. The earliest solvated examples were referred to as Zintl ions. Synthetic explorations have now established that many of the clusters can in fact be obtained from neat (solvent free) high-temperature reactions of binary to quaternary systems, particularly for the heavier tetrel (group 14) and triel (group 13) elements. Some synthetic tricks have also proven useful. Electronic guidelines such as Wade's rules, known to account well for other types of electron-deficient cluster bonding, are widely applicable to these compounds, but numerous hypoelectronic (electron-poor) trielide salts have also been discovered. These developments also extend to related infinite network structures and Zintl (valence) compounds. The Zintl boundary designation traditionally delineated the tetrel elements that form salts with the active metals from those of the triel and earlier elements that were once thought to generate only intermetallic phases. The distinction no longer seems appropriate, at least with regard to some alkali-metal compounds of the triel elements.     

Low-energy isomer identification, structural evolution, and magnetic properties in manganese-doped gold clusters MnAu(n) (n = 1-16)

The size-dependent electronic, structural, and magnetic properties of Mn-doped gold clusters have been systematically investigated by using relativistic all-electron density functional theory with generalized gradient approximation. A number of new isomers are obtained for neutral MnAu(n) (n = 1-16) clusters to probe the structural evolution. The two-dimensional (2D) to three-dimensional (3D) transition occurs in the size range n = 7-10 with manifest structure competitions. From size n = 13 to n = 16, the MnAu(n) prefers a gold cage structure with Mn atom locating at the center. The relative stabilities of the ground-state MnAu(n) clusters show a pronounced odd-even oscillation with the number of Au atoms. The magnetic moments of MnAu(n) clusters vary from 3 μ(B) to 6 μ(B) with the different cluster size, suggesting that nonmagnetic Au(n) clusters can serve as a flexible host to tailor the dopant's magnetism, which has potential applications in new nanomaterials with tunable magnetic properties.     

Metalloid aluminum and gallium clusters: element modifications on the molecular scale?

As members of the same group in the periodic table, the industrially significant elements aluminum and gallium exhibit strong similarities in the majority of their compounds. In contrast there are significant differences in the structures of the two elemental forms: Aluminum forms a typical closest-packed metallic structure whereas gallium demonstrates a diversity of molecular bonding principles in its seven structural modifications. It can therefore be expected that differences between Al and Ga compounds will arise when, as for the elemental forms, many metal-metal bonds are formed. To synthesize such cluster compounds, we have developed the following synthesis procedure: Starting from gaseous monohalides at around 1000 degrees C, metastable solutions are generated from which the elements ultimately precipitate by means of a disproportionation reaction at room temperature. On the way to the elemental forms, molecular Al and Ga cluster compounds can be obtained by selection of suitable ligands (protecting groups), in which a core of Al or Ga atoms are protected from the formation of the solid element by a ligand shell. Since the arrangement of atoms in such clusters corresponds to that in the elements, we have designated these clusters as metalloid or elementoid. In accordance with the Greek word [see text] (ideal, prototype), the atomic arrangement in metalloid clusters represents the prototypic or ideal atomic arrangement in the elements at the molecular level. The largest clusters of this type contain 77 Al or 84 Ga atoms and have diameters of up to two nanometers. They hold the world record with respect to the naked metal-atom core for structurally characterized metalloid clusters.     

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.     

Nanoalloy formation of Ta-containing trimetallic small clusters

Trimetallic cluster ions containing Ta and other metal elements were prepared in the gas phase by a triple laser-ablation technique in a controlled manner. We have measured the abundances and their thermal stabilities, using time-of-flight mass spectrometry. Taking advantage of specific abundance distribution of the trimetallic cluster ions (magic stoichiometry), relative to the distinguished stabilities, the coalescence or the segregation of Ta and the other elements in the subnanometer sized clusters was discussed. We found that Nb, W, and Mo, which are categorized as elements with a high heat of vaporization, readily coalesce with Ta, while V, Al, Co, and Pt, which are categorized as elements with a low heat of vaporization, tend to be segregated from Ta. Our experiments, along with the calculation by another research group, suggest that the binding energies of atoms are related to the coalescence or segregation of clusters in the gas phase.     

Hydrogen dissociative chemisorption and desorption on saturated subnano palladium clusters (Pdn, n = 2-9)

H(2) sequential dissociative chemisorption on small palladium clusters was studied using density functional theory. The chosen clusters Pd(n) (n = 2-9) are of the lowest energy structures for each n. H(2) dissociative chemisorption and subsequent H atom migration on the bare Pd clusters were found to be nearly barrierless. The dissociative chemisorption energy of H(2) and the desorption energy of H atom in general decrease with the coverage of H atoms and thus the catalytic efficiency decreases as the H loading increases. These energies at full cluster saturation were identified and found to vary in small energy ranges regardless of cluster size. As H loading increases, the clusters gradually change their bonding from metallic character to covalent character. For the selected Pd clusters, the capacity to adsorb H atoms increases almost proportionally with cluster size; however, it was found that the capacity of Pd clusters to adsorb H atoms is, on average, substantially smaller than that of small Pt clusters, suggesting that the catalytic efficiency of Pt nanoparticles is superior to Pd nanoparticles in catalyzing dissociative chemisorption of H(2) molecules.     

Anion photoelectron spectroscopy of germanium and tin clusters containing a transition- or lanthanide-metal atom; MGe(n)- (n = 8-20) and MSn(n)- (n = 15-17) (M = Sc-V, Y-Nb, and Lu-Ta)

The electronic properties of germanium and tin clusters containing a transition- or lanthanide-metal atom from group 3, 4, or 5, MGe(n) (M = Sc, Ti, V, Y, Zr, Nb, Lu, Hf, and Ta) and MSn(n) (M = Sc, Ti, Y. Zr, and Hf), were investigated by anion photoelectron spectroscopy at 213 nm. In the case of the group 3 elements Sc, Y, and Lu, the threshold energy of electron detachment of MGe(n)(-) exhibits local maxima at n = 10 and 16, while in the case of the group 4 elements Ti, Zr, and Hf, it exhibits a local minimum only at n = 16, associated with the presence of a small bump in the spectrum. A similar behavior is observed for MSn(n)(-) around n = 16, and these electronic characteristics of MGe(n) and MSn(n) are closely related to those of MSi(n). Compared to MSi(n), however, the larger cavity size of a Ge(n) cage allows metal atom encapsulation at a smaller size n. A cooperative effect between the electronic and geometric structures of clusters with a large cavity of Ge(16) or Sn(16) is discussed together with the results of experiments that probe their geometric stability via their reactivity to H(2)O adsorption.