Restructuring of the Ge(100) surface by Na chains

The Na-induced surface structures on Ge(100) at concentrations below 0.1 monolayer (ML) have been investigated with low-energy electron diffraction and with scanning tunneling microscopy (STM). Annealing and partial desorption of higher coverages at temperatures between 650 and 680 K lead to the formation of characteristic chain structures, alternating between uncovered Ge dimer or double dimer rows and Na chains. The Na atoms have a preferential distance of three Ge lattice constants along the chains, but there is little correlation between different chains. Locally, only commensurate distances between Na chains of 4, 6 and 8 Ge lattice constants have been detected, with average distances being either commensurate or incommensurate, depending on the Na concentration. STM suggests complete removal of Ge-dimer rows below adsorbed Na chains. These alkali induced chainlike and well ordered self-organized modulations can be used as templates to impose these structures onto adsorbed ultra-thin insulating films. © 2003 The American Physical SocietyDF

Statistische Darstellung des Kreises Büren

nach amtlichen Quellen bearb. von Frh. v. Oeynhause

The structure of cobalt nanoparticles on Ge(001)

In this contribution we present scanning tunnelling microscopy (STM) and spectroscopy (STS) investigations on isolated cobalt clusters in contact with Ge(001). Mass-filtered nanoparticles with diameters ranging from 3 to 11 nm are generated using an arc cluster ion source (ACIS) and deposited under soft landing conditions (Ekin/atom < 0.5 eV). Since the tip radius is of the same order as the nanoparticle diameters the recorded STM images are significantly affected by tip folding. By means of the “blind reconstruction method" it is possible to approximate the tip shape. After a respective deconvolution of the image structural features of the particle facets become observable. According to the equilibrium shape of the clusters being a truncated octahedron in the size range under investigation, hexagonal and rectangular features appear in the images. STS is sensitive to occupied and unoccupied states near the Fermi level and reveals the existence of distinct states in the tunnelling conductivity of the substrate as well as on the clusters. The richly structured density of states of the germanium surface serves here as tip condition test. First measurements of the tunnelling conductivity of the CoN/Ge(001) are presented and discussed

Geognostische Umrisse der Rheinländer zwischen Basel und Mainz mit besonderer Rücksicht auf das Vorkommen des Steinsalzes : nach Beobachtungen ertworfen, auf einer Reise im Jahre 1823 gesammelt

durch C. v. Oeynhausen, H. v. Dechen, H. v. La RocheBd. 1: VIII, 323, VIII, 443 Seiten, 20 cm (8°) ; Bd. 2: 1 Faltkarte, 20 cm (4°)[Karte]: Geognostische Charte der Rheinländer zwischen Basel und MainzSchuberGeschenkexlibris-Etikette: "Legat von Herrn Bergrath Stockar-Escher" Exemplar der ETH-BI

Adsorbate-induced one-dimensional long-range modulation of an epitaxial insulator film

Using low-energy electron diffraction and scanning tunneling micrsocopy, we found that epitaxial NaCl films grown on Ge(100) with thicknesses up to (at least) 15 monolayers can be modulated with a period of six lattice constants and an amplitude directed mainly normal to their surface. The (6*1) periodicity on the NaCl films is induced by a preadsorbed Na layer at very low coverages (?0.06), that form chain structures with a sixfold periodicity in one dimension. At 10 monolayers thickness of NaCl a modulation amplitude of 0.28 Å was obtained. © 2002 American Institute of Physics

Structure of AuSi nanoparticles on Si(111) from reflection high-energy electron diffraction and scanning tunneling microscopy

Gold-rich AuxSi1−x particles grown on Si(111)7 × 7 are studied by reflection high-energy electron diffraction (RHEED) and scanning tunneling microscopy (STM). The diffraction patterns reveal that (1) at least two different crystal structures coexist on the substrate; (2) the most prominent data correspond to a rhombohedral or quasi closed-packed structure; and (3) the particles show formation of an unusual contact facet to the substrate. Complete crystal alignment of the particles to the substrate lattice is found with no hints of random orientation. The findings are compared to STM images in terms of their structure, orientation, and morphology