Energy Dependence of MeV He+ Ion-Induced Re-Emission of Hydrogen Isotopes Implanted into Graphite.

Abstract

The energy dependence of MeV He+ ion-induced re-emission of hydrogen isotopes (H and D) implanted into graphite has been measured by means of the elastic recoil detection (ERD) technique in order to clarify the collision process for the ion-induced detrapping. The experimental re-emission profiles have been analyzed by solving the mass balance equations, in which the ion-induced detrapping cross section σ d and the rate constants of the retrapping Σ T and local molecular recombination K between an activated hydrogen atom and a trapped one are taken into account. The values of σ d and K/Σ T have been determined from the best-fit analytical solution to the experimental re-emission profiles. It has been found that the average values of σ d and K/Σ T for H are twice as large as those for D, which is the so-called isotope effect. It has been shown that the experimental values of σ d and their energy dependence agree well with the theoretical ones, which are calculated using the power-law approximations for Tho...