Effect of irradiation on deuterium reemission and retention in metals

In order to investigate the effect of irradiation on deuterium reemission and retention in Ni, the reemission and thermal desorption for pre-irradiated Ni under various conditions have been measured employing probing implantation of 8 × 10 19 D + / m 2 (25 keV) at 323 K. After 323 K pre-irradiation, the reemission time becomes longer and the deuterium retention is increased markedly with increasing fluence. This is due to the hydrogen trapping by the defect produced by the pre-irradiation. Although the effect of pre-irradiation above 373 K is not so significant as 323 K pre-irradiation, thermal desorption spectra show the difference. Applying the simple diffusion and trapping theory taking into account the production of the defect (trapping site) during the implantation, the thermal desorption spectra are analyzed and trapping energies of 0.77 eV and 0.91 eV for 323 K pre-irradiation are identified. Because of the lack in understanding of the correlation between the defect structures and the trapping sites, however, the temperature dependence is not well understood.