Abstract
We have performed a high resolution, high sensitivity study of the electron-positron momentum distribution in both natural and synthetic diamond, using the two-dimensional Doppler broadening technique of positron annihilation spectroscopy. The measurements were carried out with the <100>, <110> and <111> axes each separately aligned collinearly with the detectors so that the anisotropy of the momentum distribution could be mapped out. Small differences in the momentum profiles were amplified with subtraction spectra and compare well with results of a two-component density functional theory calculation of the electron-positron momentum distribution in the diamond lattice. There has been much debate regarding previously unexplained anomalies in the annihilation characteristics of the bulk positron configuration in diamond. These new results strongly support a model describing the bulk positron as delocalised and inhomogeneous, but with sufficient amplitude at the intra-bond region such that the annihilation characteristics are determined by the bond electron density and momentum distribution.
| Original language | English |
|---|---|
| Pages (from-to) | 475-478 |
| Number of pages | 4 |
| Journal | Materials Science Forum |
| Volume | 255-257 |
| DOIs | |
| Publication status | Published - 1997 |
| Externally published | Yes |
Keywords
- Coincidence Doppler Broadening Spectroscopy
- Density-Functional Theory
- Momentum Distribution
ASJC Scopus subject areas
- General Materials Science
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering