Nitric Oxide Reduction by Carbon Monoxide over Supported Hexaruthenium Cluster Catalysts. 1. The Active Site Structure That Depends on Supporting Metal Oxide and Catalytic Reaction Conditions

Tunneling Desorption of Single Hydrogen on the Surface of Titanium Dioxide

We investigated the reaction mechanism of the desorption of single hydrogen from a titanium dioxide surface excited by the tip of a scanning tunneling microscope (STM). Analysis of the desorption yield, in combination with theoretical calculations, indicates the crucial role played by the applied electric field. Instead of facilitating desorption by reducing the barrier height, the applied electric field causes a reduction in the barrier width, which, when coupled with the electron excitation induced by the STM tip, leads to the tunneling desorption of the hydrogen. A significant reduction in the desorption yield was observed when deuterium was used instead of hydrogen, providing further support for the tunneling-desorption mechanism.

Gas-phase synthesis and structure of Wade-type ruthenium carbonyl and hydrido carbonyl clusters

The gas-phase reaction of size-selected Ru(n)(+) (n = 4-6) clusters with CO in an ion trap yields only one specific ruthenium carbonyl complex for each cluster size, Ru4(CO)14(+), Ru5(CO)16(+), and Ru6(CO)18(+). First-principles density functional theory calculations reveal structures for these hitherto unknown carbonyl compounds that are in perfect agreement with the geometries predicted by Wade's electron counting rules. Furthermore, reactions with D2 show that for Ru4(+) and Ru6(+), CO molecules can be partially replaced by D2 to form hydrido carbonyl complexes while preserving the total ligand count corresponding to the Wade cluster sizes.