Detection of deuterium trapping sites in tungsten by thermal desorption spectroscopy and positron annihilation spectroscopy

Comparative Passivation of Si(100) by H2 and D2 Atmospheres under Simultaneous Xe+ Bombardment: An X-ray Photoelectron Spectroscopy Analysis

This study presents a comparison of H2 and D2 passivation on Si(100) under simultaneous Xe+ ion bombardment. The impact of Xe+ ions causes significant damage to the substrate surface, leading to an increase in H2 (D2) retention as Si-H (Si-D) bonds. The ion bombardment conditions are precisely controlled using a Kaufman ion gun. The atomic concentrations on the surface of the sample were investigated by quasi-in situ X-ray photoelectron spectroscopy. A simple methodology is employed to estimate the H (D) chemical concentration and the cover ratio of the sample, with regard to the oxygen concentration through residual water chemisorption present in the vacuum vessel. Differences in passivation are expected when using H2 or D2 atmospheres because their retained scission energies and physisorption properties differ. The results indicate an increase of the sticking coefficient for D2 and H2 under the ion bombardment. It is also found that the flux of H2 (D2) impinging on the surface contributes to play an important role in the whole process. Finally, a model is proposed to describe the phenomenon of the passivation of Si under Xe+ ion bombardment in the presence of H2 (D2).

Novel Methods for Prevention of Hydrogen Embrittlement in Iron

Iron is the most widely used metal in the world. However, hydrogen embrittlement in steels—iron based alloys—is an important issue related to the safety of our infrastructure, such as railroads and bridges. Therefore, the prevention of hydrogen embrittlement in steels is necessary. In the present study, we demonstrate two novel methods for the prevention of hydrogen embrittlement in iron: one involves the low-energy implantation of helium, which is usually an element harmful to metals, into iron, the other is inducing damage to the iron surface by ion irradiation. In general, irradiation with high-energy particles leads to metal brittleness. In the former method, the driving force for hydrogen embrittlement in iron is weakened, in the latter method, hydrogen diffusion in iron is prevented because of trapping of hydrogen atoms in the vacancies produced by the irradiation. As a result, hydrogen embrittlement in iron was suppressed by both methods.