Temperature dependence of electric-field gradients at isolated Se adatoms on (001) and (111) surfaces and derived adatom distances
Abstract
Increasing electric-field gradients (EFG) with increasing temperature were observed at isolated Se adatoms on Ni(111), Pd(111), and Co(0001) surfaces applying perturbed angular correlation spectroscopy. This is in contrast to EFG's at probes on surfaces with (001) orientation and in metallic bulk systems. We correlate the results with the EFG dependence on the adatom distance from the surface, as calculated by the discrete variational method molecular/cluster method. The sign changes from negative EFG's on (001), to positive EFG's on (111) surfaces. The distance of isolated Se atoms will be compared with measurements of concentrated Se coverage.
- Publication:
-
Physical Review B
- Pub Date:
- August 2001
- DOI:
- 10.1103/PhysRevB.64.081404
- Bibcode:
- 2001PhRvB..64h1404W
- Keywords:
-
- 73.20.Hb;
- 71.15.Mb;
- 76.80.+y;
- Impurity and defect levels;
- energy states of adsorbed species;
- Density functional theory local density approximation gradient and other corrections;
- Mossbauer effect;
- other gamma-ray spectroscopy