Hydrogen adsorption and reaction on the Ir{100}-(1×5) surface

Adsorption of hydrogen (deuterium) on the Ir{100} surface has been studied with low-energy electron diffraction (LEED) and temperature-programmed desorption (TPD). At least three well-defined peaks can be identified with peak temperatures (Tp) of 125, 240 and 375 K in the TPD spectrum for the surface saturated with H at ∼100 K. From the LEED observations, it can be concluded that these three peaks in the TPD spectrum correspond to H2 desorption from the (1×5), (1×3), and (1×1) restructured phases, respectively. Furthermore, the result suggests that a metastable state of (1×3) exists on the Ir{100} surface in addition to the (1×1) phase. The series of TPD spectra for coadsorption of H2 and D2 on the Ir{100} surface show that an energetic D(H) atom produced in the dissociation process of incident D2(H2) replaces a preadsorbed H(D) atom via energy transfer, and the expelled H(D) atom moves to another adsorption site.