Kinetic effects of subsurface species on Zr(0 0 0 1) surface chemistry

Zirconium alloys are widely used in chemical and nuclear engineering applications because of their high corrosion resistance and low neutron cross-sections. However, fundamental studies of relevant model systems are sparse, leaving open-questions regarding the surface chemistry of this class of materials. In an effort to answer some of these questions, we have been studying the kinetics and reaction mechanisms of small molecules (water, ammonia, nitric oxide) adsorbed on Zr(0 0 0 1) surfaces under ultra-high vacuum conditions. The data from these systems indicate that kinetic surface/subsurface exchange plays a major role in the resulting surface chemistry and show strong adsorption temperature effects. In this paper we summarize the results of our studies and present a conceptual model which accounts for our experimental findings.