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Persistence of the Nb(100) Surface Oxide Reconstruction at Elevated Temperatures

Helium atom scattering and Auger electron spectroscopy (AES) are used to characterize the (3 × 1)-O reconstruction of the Nb(100) surface at elevated temperatures. Persistent helium diffraction peaks and specular lineshape analysis indicate that the …

Suppression of Nano-Hydride Growth on Nb(100) due to Nitrogen Doping

Niobium superconducting radio frequency (SRF) cavities enable the operation of modern superconducting accelerator facilities. These cavities do not approach the theoretical performance limits of Nb due to the deleterious effects of surface defects …

Temperature Dependence of CO Oxidation on Rh(111) by Adsorbed Oxygen

Carbon monoxide oxidation over oxidized Rh surfaces is known to be sensitive to both the oxygen species present as well as the surface temperature. Although CO oxidation on Rh(111) is a prototypical heterogeneously catalyzed oxidation reaction, …

Characterization of Oxygenaceous Species Formed by Exposure of Ag(111) to Atomic Oxygen

The uptake and chemical speciation of oxygen in and on Ag(111) surface is described. An Ag(111) surface was exposed to gas-phase oxygen atoms under ultrahigh vacuum compatible conditions at various surface temperatures. The O uptake was quantified …

Oxygen Dissolution and Surface Oxide Reconstructions on Nb(100)

The ever-present native oxide layer on niobium plays a fundamental role in the performance of Nb superconducting radio frequency (SRF) cavities for particle accelerators and light sources. Using Nb(111) and Nb(100) as model systems, oxygen …

Identification of Surface Sites for Low-Temperature Heterogeneously Catalyzed CO Oxidation on Rh(111)

In heterogeneously catalyzed oxidation reactions on metal surfaces, advantageous oxygenaceous species proffer lower barrier reaction pathways. In order to utilize such reactions better, it is essential to understand what species are present, how they …

The Quest for Stability: Structural Dependence of Rh(111) on Oxygen Coverage at Elevated Temperature

Recent studies have shown the importance of oxide surfaces in heterogeneously catalyzed reactions. Because of the difficulties in reproducibly preparing oxidized metal surfaces, it is often unclear what species are thermodynamically stable and what …

Exposure of Pt(553) and Rh(111) to Atomic and Molecular Oxygen: Do Defects Enhance Subsurface Oxygen Formation?

Subsurface oxygen is known to form in transition metals, and is thought to be an important aspect of their ability to catalyze chemical reactions. The formation of subsurface oxygen is not, however, equivalent across all catalytically relevant …

Step-Type Selective Oxidation of Pt Surfaces

We report on a combined TPD and STM study of O2 adsorption and dissociation on various Pt surfaces with varying (111) terrace widths and either (110) or (100) step geometries. Our quantitative TPD results show that (110) stepped surfaces adsorb …

Thermally Selective Formation of Subsurface Oxygen in Ag(111) and Consequent Surface Structures

A long-standing challenge in the study of heterogeneously catalyzed reactions on silver surfaces has been the determination of what oxygen species are of greatest chemical importance. This is due to the coexistence of several different surface …