Reaction kinetics of atomic hydrogen with deuterium on Ni(110)

The interaction of atomic hydrogen with clean and deuterium precovered Ni(110) surfaces at 150 K has been investigated using thermal desorption mass spectrometry. The initial sticking coefficient of atomic hydrogen is 0.9 +/- 0.1. Above saturation at 1.5 monolayers for dissociative H-2 adsorption, atomic hydrogen absorption leads to the occupation of subsurface sites with a penetration probability of 1 x 10(-2). Impingement of atomic hydrogen on a deuterium covered Ni(110) surface leads to deuterium abstraction via HD production with a removal coefficient of 0.26 HD molecules per H-atom (Eley-Rideal mechanism). In addition, removal of deuterium by associative D-2 desorption has been observed at T-s = 150 K, with a removal coefficient of 0.04 D-2 molecules per H-atom (collision induced recombinative Langmuir-Hinshelwood desorption). Interaction of atomic deuterium with a hydrogen covered surface yields an HD removal coefficient of 0.38 HD molecules and an H-2 removal coefficient of 0.06 H-2 molecules per D-atom.