Abstract
We measured the diffusion coefficients for hydrogen (H) and deuterium (D) on Ni(111) from 108 to 154 K. We observed nonactivated tunneling following thermally activated hopping at around 125 K for both isotopes. The nonactivated tunneling rates show weak isotope dependence. Our observation confirms an early report by Lin and Gomer [Surf. Sci. 225, 41 (1991)]. The nonactivated tunneling is analyzed with both a modified polaron model, which includes adatom-phonon couplings varying quadratically in phonon coordinates, and the conduction electron model. The weak isotope dependence is understood as a result of a large WKB tunneling matrix element on Ni(111).
Original language | English (US) |
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Pages (from-to) | 11256-11259 |
Number of pages | 4 |
Journal | Physical Review B |
Volume | 48 |
Issue number | 15 |
DOIs | |
State | Published - 1993 |
ASJC Scopus subject areas
- Condensed Matter Physics