Phase transitions in two dimensions - the case of Sn adsorbed on Ge(111) surfaces

Accurate atomic coordinates of the room-temperature (root3xroot3)R30degree and low-temperature (3x3) phases of 1/3 ML Sn on Ge(111) have been established by grazing-incidence x-ray diffraction with synchrotron radiation. The Sn atoms are located solely at T4-sites in the (root3xroot3)R30degree structure. In the low temperature phase one of the three Sn atoms per (3x3) unit cell is displaced outwards by 0.26 +/- 0.04 A relative to the other two. This displacement is accompanied by an increase in the first to second double-layer spacing in the Ge substrate.Comment: RevTeX, 5 pages including 2 figure

Comment on 'Structural model for the Si(001)4×3Si ( 001 ) 4 × 3-In surface phase'

Surface x-ray diffraction investigations of the indium-induced Si(001)−(4×3) reconstruction show that the modulated (4×1) structure recently proposed by Zotov et al. [Phys. Rev. B 57, 12 492 (1998)] is not correct. The experimental data are incompatible with calculations of the fractional order rods using this model. A complex pyramidlike reconstruction [O. Bunk et al., Appl. Surf. Sci. 123/124, 104 (1998)] explains all the available experimental data

Ge tetramer structure of the p ( 2 2 × 4 2 ) R 45 ° surface reconstruction of Ge/Ag(001): A surface x-ray diffraction and STM study

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Structure determination of the indium induced Si(001)-(4 × 3) reconstruction by surface X-ray diffraction and scanning tunneling microscopy

The indium-induced Si(001)-(4 × 3) reconstruction has been investigated by surface X-ray diffraction (SXRD) measurements with synchrotron radiation and scanning tunneling microscopy (STM). The Patterson function analysis enables us to exclude In dimers as a structural element in this reconstruction. We present a new structural model which includes 6 In atoms threefold coordinated to Si atoms and 5 displaced Si atoms per unit cell. Relaxations down to the sixth layer were determined. ‘Trimers’ made up of InSiIn atoms are a key structural element

Surface structure of Au3Cu(001)Au_3Cu(001)

The surface morphology, composition, and structure of Au3Cu(001) as determined by scanning tunneling microscopy and surface x-ray diffraction are presented. Atomic resolution STM images reveal distinctive geometric features. The analysis of the surface x-ray diffraction data provides clear evidence of gold enrichment of the topmost layer with two different gold positions and only a small copper fraction. The second layer has approximately Cu4Au stoichiometry, whereas the third layer is pure gold. STM images and SXRD results are in excellent agreement and reveal a detailed atomic model for the surface structure