Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan.
J Phys Chem A. 2011 Oct 27;115(42):11479-85. doi: 10.1021/jp202125g. Epub 2011 Oct 4.
Titanium oxide clusters were formed in the gas phase by the laser ablation of a Ti rod in the presence of oxygen in a He gas. Not only stoichiometric but also nonstoichiometric titanium oxide clusters, Ti(n)O(2n+x)(+) (n = 1-22 and x = -1-3), were formed. The content of oxygen atoms depends strongly on a partial pressure of oxygen. Gold clusters, Au(m) (m = 1-4), were generated by the laser ablation, which were then deposited on Ti(n)O(2n+x) clusters. The formation of Au(m)Ti(n)O(2n+x)(+) follows electron transfer from Au(m) to Ti(n)O(2n+x)(+). The reactivity of Au(m)Ti(n)O(2n+x)(+) cluster ions with CO was examined for different m, n, and x by the mass spectrometry. It was found that Au(m) on Ti(n)O(2n-1)(+) are less reactive than those on the other Ti(n)O(2n+x)(+) (x = 0 and 1). In addition, the reactivity is highest when Au(m) (m = 1 and 3) is on the stoichiometric titanium oxide (x = 0), whereas the reactivity is also high when Au(2) is on the oxygen-rich titanium oxide (x = 1). The reactivity was found to relate to geometrical structures of Au(m)Ti(n)O(2n+x)(+), which were studied by density functional calculations.
钛氧化物团簇通过激光烧蚀钛棒在氦气中存在氧气的条件下在气相中形成。不仅形成了化学计量比的钛氧化物团簇，还形成了非化学计量比的钛氧化物团簇，Ti(n)O(2n+x)(+)（n = 1-22，x = -1-3）。氧原子的含量强烈依赖于氧气的分压。通过激光烧蚀产生了金团簇，Au(m)（m = 1-4），然后沉积在 Ti(n)O(2n+x)团簇上。Au(m)Ti(n)O(2n+x)(+)的形成遵循从 Au(m)到 Ti(n)O(2n+x)(+)的电子转移。通过质谱法研究了不同 m、n 和 x 时 Au(m)Ti(n)O(2n+x)(+)团簇离子与 CO 的反应性。发现 Ti(n)O(2n-1)(+)上的 Au(m)比其他 Ti(n)O(2n+x)(+)（x = 0 和 1）上的 Au(m)的反应性低。此外，当 Au(m)（m = 1 和 3）在化学计量比的钛氧化物（x = 0）上时，反应性最高，而当 Au(2)在富氧钛氧化物（x = 1）上时，反应性也很高。通过密度泛函计算研究了 Au(m)Ti(n)O(2n+x)(+)的几何结构，发现反应性与 Au(m)Ti(n)O(2n+x)(+)的几何结构有关。
