Ir{1 0 0}-(1×3)-H, an intermediate phase between the (1×1) and the (1×5) phases of Ir{1 0 0}

Clean Ir{1 0 0} surfaces reconstruct to form a (1×5) overlayer. When hydrogen adsorbs on Ir{1 0 0}, a metastable (1×3) phase is formed. Temperature programmed desorption results show that hydrogen is needed to stabilise this phase. When hydrogen is desorbed the structure reverts back immediately to the (1×5) phase. The (1×3) structure has been determined using quantitative low energy electron diffraction. The best-fit structure has three iridium and five hydrogen atoms per unit cell. Two of the hydrogens lie in the subsurface region and stabilise the (1×3) phase.