Abstract
Angular distribution of backward re-emitted positrons from a W(100) single crystal have been measured for incident positron energies of 250 and 600 eV. The width of the angular distribution was broader than that predicted by a model of re-emission that assumes complete thermalization of positrons in the solid. Angle-resolved energy distribution of re-emitted positrons showed that the mean energy of the emitted positrons increased with angular deviation from normal. The increase is explained in terms of energy-dependent refraction of positrons traversing the potential step at the surface. The results are in qualitative agreement with a one-dimensional step model of positron re-emission. The observed angular distribution and energy distributions qualitatively matched calculated data if a sample effective temperature of four times the actual temperature is assumed. This suggests the emission of incompletely thermalized positrons at low energy of incident positrons. © 2013 American Physical Society.
Original language | English |
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Pages (from-to) | 6pp |
Journal | Physical Review B |
Volume | 87 |
Issue number | 8 |
DOIs | |
Publication status | Published - 2013 |