Self-assembled growth of an ordered layer of Pt-Br-Pt chains on a Pt(110) surface is demonstrated. Upon slight doping with excess bromine, charge-density wave (CDW) domains separated by well-localized solutions are observed in the Br/Pt layer by scanning tunneling microscopy. Depending on annealing and adatom concentration, a global, long-range-ordered CDW ground state can be established. Angle-resolved UV photoemission data reveal the corresponding Fermi surface and its removal upon the Peierls transition. The CDW phase is stable to well above room temperature.

We present a detailed investigation of the c(2ϫ2)-Br/Pt(110) adlayer structure supplemented by the analysis of the (1ϫ2) missing-row ͑MR͒ structure of the clean Pt͑110͒ surface. Quantitative low energy electron diffraction analyses and first-principles calculations are in impressive agreement in both cases. The clean surface reconstruction is determined with unprecedented accuracy. For the adsorbate, the analysis retrieves a simple Br-adlayer structure with the Br atoms residing in every second short bridge position on the closepacked Pt rows with the MR reconstruction lifted. The Br-Pt bond length Lϭ2.47 Å is almost equal to the sum of the atomic radii. The substrate below the adsorbate exhibits a contraction of the first layer spacing which amounts to half of that calculated for an unreconstructed clean surface.

After our recent report on the formation of a (3ϫ1) charge-density-wave phase in the quasi-onedimensional system Br/Pt͑110͒ we present a detailed investigation of the c(2ϫ2)⇒(3ϫ1) transition in the Br/Pt͑110͒ adsorption system. This includes the atomic structure of the (3ϫ1) phase as determined by quantitative low-energy electron diffraction ͑LEED͒ and density functional theory calculations. While in the parent c(2ϫ2) phase with coverage ⌰ϭ1/2 ML the Br atoms occupy every second short-bridge site on the unreconstructed (1ϫ1)-Pt͑110͒ surface, the adatoms in the (3ϫ1) phase at coverage ⌰ϭ2/3 ML reside in every third short-bridge and long-bridge sites. Charge densities and vertical relaxations of the Pt atoms forming the short-and long-bridge sites are different, thus yielding a modulation of both, the charge and the position of the outermost Pt atoms with a period of three nearest-neighbor spacings. For 1/2 MLϽ⌰р0.58 ML LEED intensity and scanning tunneling microscope ͑STM͒ measurements reveal the nucleation of (3ϫ1) islands surrounded by areas with a local coverage of 1/2 ML. Within the latter areas the STM measurements indicate dynamical fluctuations of the Br positions at room temperature. In the time average every short-bridge site is sampled by the mobile Br atoms, but in the neighborhood of (3ϫ1) islands every third short-bridge site seems to be preferentially occupied.

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