摘要
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 .
An observation is demonstrated that Au/S target, triggered by gallium ion beam (Ga-69(+)) under experiment of high performance secondary ion mass spectrometry (TOF SIMS), does emit a considerable species of cluster negative ions with general formula of An(1-15)So(0-5) (see Fig. 1 and Table 1). Among them, a series of cluster ions with compositions of Au1-15S1-5 is recognized as Au-S binary cluster ions, while other series with Au1-15 belongs to mono-cluster ions of pure gold, appearing in strong odd-predominance of their intensities with number of gold atom (see Fig. 2). The Au-S cluster ions can be characterized, in some aspects, by existence of the odd-predominance with magnitudes of gold atom (see Fig. 3), inherited from the An mono-clusters; by lack of stoichiometric feature, showing that gold atoms range from 1 to 15 but sulfur atoms are always limited to 5 (see Table 1); by void of predominance as compositions as MenSn (for example, CunSn, see Table 2) or MenNn whose priority has been proved as an important feature prevailing in other binary cluster ions of metals (Me) plus sulfur (S) or other non-metals (N); and by presence of special profiles as similar as those of C-P binary cluster ions, a series of typical non-metal-binary ones (see, Ref. 23). These facts suggest that the speciation of Au-S cluster ions probably comes from a constitution of relatively intact An mono-clusters, and thus imply in gaseous-phase mechanism that a binary aggregation between Au mono-clusters and S mono-clusters or the confined poly-sulfur units might contribute to the formation of the Au-S binary cluster ions. The aggregation may be based on covalent bindings between the end groups of the two clusters, or on a non-covalent interaction between the clusters, such as electrostatic gravitation between hetero-atoms or hetero-molecules, but its true mechanism remains to be resolved in future work.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2001年第9期859-864,共6页
Acta Physico-Chimica Sinica
基金
国家自然科学基金资助项目(40043010)
关键词
金-硫团簇
再团簇化
团簇负离子
组成特征
团簇化机制
静态二次离子质谱
Au-S binary clusteri ons
Au mono-cluster
five-sulfur units
aggregation
cluster negative ions
compositional characterization
TOF SIMS
