title: Gas phase synthesis of Au clusters deposited on titanium oxide clusters and their reactivity with CO molecules.
abstract: 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.
authors: Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan.
authors: Hidenori
authors: H
authors: Himeno
authors: Ken
authors: K
authors: Miyajima
authors: Tomokazu
authors: T
authors: Yasuike
authors: Fumitaka
authors: F
authors: Mafuné