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

Adsorption of hydrogen (deuterium) on the Ir{100} surface has been studied with low-energy electron diffraction (LEED) and temperature-programmed deso rption (TPD). At least three well-defined peaks can be identified with peak temperatures (T-p) of 125, 240 and 375 K in the TPD spectrum for the surfa ce saturated with H at similar to 100 K. From the LEED observations, it can be concluded that these three peaks in the TPD spectrum correspond to Hz d esorption from the (1 x 5), (1 x 3), and (1 x 1) restructured phases, respe ctively. Furthermore, the result suggests that a metastable state of(1 x 3) exists on the Ir{100} surface in addition to the (1 x 1) phase. The series of TPD spectra for coadsorption of H-2 and D-2 on the Ir{100} surface show that an energetic D(H) atom produced in the dissociation process of incide nt D-2(H-2) replaces a preadsorbed H(D) atom via energy transfer, and the e xpelled H(D) atom moves to another adsorption site. (C) 2000 Elsevier Scien ce B.V. All rights reserved.