We measured the temperature and azimuthal dependence of the diffusion rates of hydrogen (1H) and deuterium (2H) on Ni(111) from 65 to 240 K where the diffusion rates vary by 8 orders of magnitude. The diffusion of hydrogen crosses over from an activated behavior above 110 K to another activated behavior below 110 K with a smaller activation energy. By ruling out the possibility of a step effect, we suggest that the crossover is from a classical overbarrier hopping to a quantum mechanical underbarrier tunneling.
|Original language||English (US)|
|Number of pages||4|
|Journal||Physical Review Letters|
|State||Published - Nov 10 1997|
ASJC Scopus subject areas
- Physics and Astronomy(all)