The chemical state of interface between Pd and Mg layers has been investigated by XPS and NEXAFS methods. Since it is thought that the hydrogen storage ability strongly depends on the chemical state of the interface, we focus on the interface of the Pd-Mg. It is found that the different phase from bulk metal or oxide exists between Pd and Mg layers prepared by both DC magnetron sputtering and vacuum evaporation methods. From XPS and NEXAFS measurements, we have revealed that Pd loses the electron and Mg picks up one in this phase. It might be thought that the Pd-Mg alloy phase exists between Pd and Mg.
The size dependence of the air oxidation for Mg nanoparticles is studied by Mg K-edge NEXAFS and AFM techniques. In the case of the exposure to the air for 3 days, the degree of the air oxidation for Mg nanoparticles increases with reduction of the size of Mg nanoparticle. However, the opposite size dependence is observed in the case of the exposure to the air for 25 days, i.e. the air oxidation reaction for the smaller Mg nanoparticles is more inhibited in the case of long term exposure to the air. This size dependence is attributed to the occupation of the free spaces between Mg nanoparticles, which protects against the incursion of the air component molecules into the multilayer of Mg nanoparticles.
A dissociation reaction of (CH3)2S (dimethyl sulfide; DMS) on a Pd capped Mg layer surface has been studied by using Sulfur K-edge Near Edge X-ray Absorption Fine Structure (NEXAFS) technique. The Pd thin film is prepared by two deposition methods, one is vacuum deposition, and the other is DC magnetron sputtering. The surface morphology is observed by Atomic Force Microscopy (AFM). The AFM observation reveals that there are many nano sized particles on the Pd/Mg surface, and an average size of the particle prepared by DC magnetron sputtering is obviously smaller than that prepared by vacuum deposition. NEXAFS analysis reveals that DMS dissociation is weakened on the Pd surface prepared by DC magnetron sputtering and promoted on the Pd surface prepared by vacuum deposition. It seems that any adsorption reactions are promoted on small sized metal particles, however, the DMS dissociation reaction is promoted on the Pd surface prepared by vacuum deposition, which has big sized Pd particles.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.