Time-dependent diffusion and annihilation of positrons implanted in a semi-infinite medium
D T Britton; D T Britton; Inst. fur Nukleare Festkorperphys., Univ. der Bundeswehr Munchen, Neubiberg, West Germany
Журнал:
Journal of Physics: Condensed Matter
Дата:
1991-02-11
Аннотация:
Annihilation spectra, resulting from the implantation of mono-energetic positrons in a perfect homogeneous solid, have been modelled allowing for the transport of both thermal and epithermal positrons. The resulting curves resemble a sum of two exponential components, although the intensities are not simply related to the positron back-diffusion probability. Because of the very short times involved, the effects of nonthermal positron transport are less significant than for steady-state diffusion models. At room temperature, internal reflection of thermal positrons at the surface has little effect on the solution to the diffusion equation for deeply implanted positrons.
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