Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA.
J Chem Phys. 2010 Feb 7;132(5):054305. doi: 10.1063/1.3299292.
A variety of experimental techniques are used to resolve energetically close isomers of Au(7)(-) and Au(8)(-) by combining photoelectron spectroscopy and ab initio calculations. Two structurally distinct isomers are confirmed to exist in the cluster beam for both clusters. Populations of the different isomers in the cluster beam are tuned using Ar-tagging, O(2)-titration, and isoelectronic atom substitution by Cu and Ag. A new isomer structure is found for Au(7)(-), which consists of a triangular Au(6) unit with a dangling Au atom. Isomer-specific photoelectron spectra of Au(8)(-) are obtained from O(2)-titration experiment. The global minimum and low-lying structures of Au(7)(-), Au(8)(-), and MAu(n)(-) (n=6,7; M=Ag,Cu) are obtained through basin-hopping global minimum searches. The results demonstrate that the combination of well-designed photoelectron spectroscopy experiments (including Ar-tagging, O(2)-titration, and isoelectronic substitution) and ab initio calculation is not only powerful for obtaining the electronic and atomic structures of size-selected clusters, but also valuable in resolving structurally and energetically close isomers of nanoclusters.
多种实验技术被用于通过结合光电子能谱和从头计算来分辨金（7）（-）和金（8）（-）的能量相近的异构体。两种结构不同的异构体被确认为这两个团簇在团簇束中存在。使用氩标记、O2 滴定和 Cu 和 Ag 的等电子原子取代来调节团簇束中不同异构体的比例。发现了金（7）（-）的一种新的异构体结构，它由一个带有悬空金原子的三角形 Au6 单元组成。通过 O2 滴定实验获得了 Au8- 的异构体特异性光电子能谱。通过 basin-hopping 全局最小搜索获得了 Au7-、Au8- 和 MAu（n）-（n=6，7；M=Ag，Cu）的全局最小和低能结构。结果表明，精心设计的光电子能谱实验（包括氩标记、O2 滴定和等电子取代）与从头计算的结合不仅对于获得尺寸选择的团簇的电子和原子结构非常有效，而且对于分辨纳米团簇的结构和能量相近的异构体也非常有价值。
